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THE History of Geology and Paleontology was originally en- 
trusted to Julius Ewald of Berlin. The Historical Commission 
of the Bavarian Royal Academy of Sciences could not have 
made a happier choice. Ewald was one of the few geologists 
who had been actively engaged in geological research during 
the first half of the nineteenth century; he had witnessed the 
most brilliant period of the rise of geology in Germany, and 
had been for a long time personally acquainted with most of 
the great exponents of the science on the Continent. Unfor- 
tunately it was not granted to Ewald to bring his task to 
completion. A few years before his death his feeble health 
compelled him to give up the work he had undertaken, and 
the results of many years' labour which he had expended upon 
it were entirely lost, as his will directed that all his unfinished 
manuscripts should be destroyed. 

Although the present author of the History of Geology was 
asked to depict chiefly the history of the growth of the science 
in Germany, the nature of the subject is such that it could not 
be successfully treated along national lines. All civilised 
nations have shared in the development of the natural sciences, 
the history of any one of which must be to a certain extent 
the history of a scientific freemasonry. The questions of the 
highest import in Geology and Palaeontology are in no way 
affected by political frontiers, and the contributions to the 



progress of these studies made by members of any nationality 
can only be appreciated in their true values when held in the 
balance with the general position of research at the time, and 
with the discoveries and advances made by other geologists 
irrespective of nationality. 

In spite of some doubt and consideration on my part, it 
seemed absolutely necessary to continue the History of Geology 
and Palceontology to the present day. A historical exposition 
of these sciences which should close with the sixth or even 
the eighth decade of the nineteenth century, would be out of 
date in many respects and out of touch with the modern 
standpoint. My . task was made more difficult by such an 
extension of the subject-matter, as there has been no previous 
historical work dealing with the newer researches. Further, 
the mode of treatment which appeared most suitable for the 
older periods could not be retained with advantage for the 
treatment of the modern development. The greater and 
greater specialisation and branching of the science which took 
place during the latter half of the nineteenth century, seemed 
to demand individual descriptions of the different areas of 
research in preference to a general comprehensive survey of 
the leading features in all. 

The geological writings of antiquity have little scientific 
value, and they are therefore only briefly indicated. Again, the 
period subsequent to the downfall of the- Roman Empire and 
extending into the second half of the eighteenth century, 
though it has contributed a number of noteworthy observa- 
tions, is mainly conspicuous for its hypotheses. Whewel.l, 
Brocchi, Lyell, and others have depicted this older develop- 
ment of geology. Keferstein's Geschichte und Literatur der 
Geognosie is continued to the year 1840, but for the period 
from 1820 to 1840 it supplies only an enumeration of books 


and memoirs. Friedrich Hoffmann gave a much more attrac- 
tive account of the history of geology, and carried it as far as 
the year 1835. The history of geology by Sainte-Claire 
Deville covers practically the same ground, but devotes more 
than a third of the whole work to the writings of Elie de 
Beaumont. The eight volumes of D'Archiac's Histoire des 
Progres de la Geologic provide for the period 1834 to 1850, 
afterwards continued to 1859, an exhaustive discussion of all 
the geological publications that appeared during this time, 
but is a work intended primarily for the specialist. The 
chief work and the later historical writings of this eminent 
Frenchman gave the predominant place to French authors, 
and owing to his defective knowledge of German, the con- 
tributions in that language met with scant attention. 
H. Vogelsang's Philosophie der Geologie contains an interesting, 
but very subjective, historical introduction, wherein the progress 
of petrographical knowledge is more especially considered. 
Valuable contributions to the history of geology have been 
made by the fluent pen of Sir Archibald Geikie. His ad- 
mirable biographies of Sir Roderick Murchison and Sir Andrew 
Ramsay offer far more than the title indicates. With unsur- 
passed literary skill and scientific mastery of the subject, they 
describe the development of geology in Great Britain during 
the lives of these illustrious geologists. In a course of lectures 
on the Founders of Geology, Sir Archibald Geikie has given a 
series of admirable biographies from which may be culled 
a connected account of the early advances in the science of 

I have derived information from all the above-mentioned 
works; but it has usually been my endeavour to consult the 
original sources, and to form my own judgment independently 
of all books of reference. Where critical treatment was called 

Vlll " PREFACE. 

for, I have tried to preserve the strictest impartiality; in the 
case of controversial matters which have already arrived at a 
solution, I have limited myself to the objective attitude of the 

The original works of reference are cited at the conclusion 
of each chapter, and will prove useful to the more special 
student of the subject. 

Whether I have succeeded in the difficult task of writing 
a History of Geology and Palaeontology that will satisfy the 
specialist and also commend itself to every man of culture, 
must be left for my readers to decide. 


MUNICH, June 1899. 


THE text of the original has been somewhat curtailed in the 
translation, both in order to meet the wish of the author, and 
to secure uniformity with the other volumes of the Con- 
temporary Science Series. I have omitted entirely a chapter 
of seventy-seven pages on Topographical Geology, which was 
more special in character than any of the other chapters. I 
have also omitted the lists of books of reference, taking care 
to embody in the text all the more important publications ; 
and have condensed the subject-matter wherever it seemed 
possible to do so without detracting from the scientific 
value of the History. These changes have been made 
with the author's approval. It only remains to add that, 
as a former pupil of Geheimrath Professor von Zittel's, and 
one who bears very grateful feelings towards him, it has 
Jed me great pleasure to translate this work. 


ABERDEEN, October 1901. 






Various opinions about Fossils, 13; Hypotheses of the 
Earth's origin and history, 23 ; Beginnings of geological 
observation, 34; G. L. Leclerc de Buffon,4i; Volcanoes 
and earthquakes, 44. 


FROM 1790-1820 - 46-145 

Pallas and De Saussure, 49; A. G. Werner and his school, 
56; Leopold von Buch, 61 ; Alexander von Humboldt, 
64; Hutton, Playfair, and J. Hall, 67; Theories of the 
Earth's origin proposed by De Luc, De la Metherie, 
Breislak, Kant, Laplace, 75 ; Local geognostic descrip- 
tions and stratigraphy: (a) Germany, 81 ; (6) Austria- 
Hungary and the Alps, 87 ; (c) Italy, 94 ; (d) France, 
Belgium, Holland, and the Iberian Peninsula, 100; (e) 
Great Britain, 108; (/) Scandinavia and Russia, 115; 
(^) America, Asia, Australia, Africa, 119; Progress of 
Petrography: Neptunists, Volcanists, and Plutonists, 
122; Palxontology, 125; Text-books and handbooks of 
Geognosy and Geology, 142. 




General survey, 145 ; The influence of the Universities, 
of Geological Societies, and of the Geological Survey 
Departments, 146. 


Cosmogony, 153; The Sun, 156; The fixed stars ,and 
planets, 157; The Moon, 161 ; Meteorites and falling 
stars, 163 ; Geogeny, 166. 


Form, size, and weight of the Earth, 174; The Earth's 
internal heat and the constitution of its interior, 175 ; 
Morphology of the Earth's surface, 181. 



General survey, 1 86 ; Carl von Hoff, 187 ; Sir Charles 
Lyell, 189 ; (a) Geological action of the atmosphere, 197 ; 
(b) Geological action of water Springs, 200 ; Chemical 
action of water, 202; Erosion, 203; Denudation, 214; 
Mechanical sediments, 215; Chemical deposits in water, 
217; (c) Geological effects of ice, 220; Glaciers, 220; 
The Ice Age, 222 ; (d) Geological action of organisms, 
239 ; Peat, 240 ; Coals, 240 ; Siliceous earth, 243 ; 
Algal and foraminiferal limestone, 243 ; Coral reefs, 245 ; 
Petroleum, 253 ; (e) Volcanoes, 254 ; (/) Earthquakes, 
280 ; (g) Secular movements of upheaval and depression, 
285 ; (//) Older dislocations in the earth's crust, 295 ; 
Tectonic structure and origin of the continents and 
mountain-chains, 306. 




PETROGRAPHY - 324-362 

Werner, 324; Nicol, 326; Ehrenberg, 326; C. F. 
Naumann, 327 ; G. Bischof, 327 ; H. Clifton Sorby, 
328 ; Ferdinand Zirkel, 329 ; Vogelsang, 329 ; Rosen- 
busch, 331; Fouque and Michel- Levy, 334; Scheerer, 
342 ; Durocher, 343 ; A. Daubree, 344 ; Origin of rocks, 
346; Teall, 349; Broegger, 350; Crystalline schists, 352; 
Metamorphism of rocks, 354 ; Dynamo-metamorphism, 
357 ; Lapworth, 360. 


General principles, 363 ; Fossil plants, 368 ; Fossil 
animals, 375 ; Protozoa, 383 ; Spongida, 386 ; Ccelen- 
terata, 388 ; Echinodermata, 392 ; Brachiopoda, 397 ; 
Mollusca, 400 , Lamellibranchiata, 401 ; Gastropoda, 
401 ; Cephalopoda, 402 ; Arthropoda, 406 ; Vertebrata, 
409; Fishes, 410; Amphibians, 412; Reptiles, 415; 
Birds, 418; Mammals, 418. 



A. The early foundations of stratigraphy, 425 ; B. 
Special stratigraphy, 438 ; (a) Archaean and pre-Cambrian 
rocks, 439 ; (b) Cambrian a'nd Silurian systems, 441 ; 
(c) Devonian system, 448 ; (</) Carboniferous system, 
450 ; (e) Permian system, 453 ; (/) Triassic system, 
459 ; () Jurassic system, 497 ; (h) Cretaceous system, 
514; (*') Tertiary system, 526; (k) Quaternary forma- 
tions, 538. 


Page 115, line i,for " J. T. Berger," read " J. F. Berger 

,, 123, ,, 6, ,, " Fleurien de Bellevue," ,, "Fleuriau." 

,, 170, ,, 22, ,, " Julius Roth," ,, "Justus." 

,, 208, 6, "Eber," " Ebel." 

,, 227, ,,31,,, " Burckhardt," "Burkhardt." 

.. 393. 2 3 "Austins," ,, "Austens." 

,, 405, ,, 10, ,, " Buckmann," ,, " Buckman." 

,, 411, ,, 36, "Traschel," ,, "Troschel." 




IN all ages there have been men who have given serious 
thought to the historical aspect of our terrestrial home, to its 
origin and its development; but any clear conception of the 
beginning of the Earth based, that is, upon scientific facts 
was as remote from the most cultured nations of antiquity as 
it is at the present day from the barbarous races of mankind. 
The polymorphous myths of the Creation represent the varying 
ideas which were formed regarding natural phenomena; the 
limit of the spiritual field of vision determined the wider or more 
circumscribed flights of imagination. The wide chasm between 
the childish Saga of Creation handed down by the Bushmen, 
Australians, Eskimos and Negroes, and the grand poetic 
conceptions of the Aryan-Germanic races of Europe, conveys 
to us the immense difference at that time in the condition of 
culture and intellectual capacity of these peoples. 

Tradition has preserved to us the cosmogenetic and geo- 
genetic views of the civilised races of the Mediterranean 
countries and of Asia, and these arouse our admiration by 
their poetry and philosophic depth. But there was no trace 
either of exact observation of natural phenomena, or of logical 
deduction from such observations. 

Amongst the ancient stories of the Creation the Babylonian 
and Jewish accounts are pre-eminent for their intuitive skill 
and for the excellence and conciseness of their language. The 


traditions of the Babylonians are recorded in the cuneiform 
inscriptions found in the ruins of Nineveh. Creation begins 
with Chaos. The gods arose before heaven and earth had 
taken shape, while the tumultuous floods of oceans were still 
intermingled in the universal chaos. The gods chose Marduk 
to be their champion against Tiamat, the disturbing, chaotic 
ocean-flood. Marduk armed himself with lightning flash and 
thunderbolt, and called the winds to his assistance. Marduk 
vanquished Tiamat, and divided his corpse into two parts; 
from the one part he created the heavens, and from the other 
'trie earth and the sea. Marduk peopled the heavens with stars, 
the dwellings of the great gods. Then followed the creation 
'of 'plants and animals, and finally the creation of the two first 
human beings out of clay. The evident agreement of the 
Babylonian and Jewish conceptions becomes even more ap- 
parent in the account of the Deluge, which was at first only 
known to us from the epic of Berosus, but has now also been 
discovered in cuneiform inscriptions. 

The Mosaic account of the Creation far excels the Baby- 
lonian in its noble simplicity and in the strength and beauty of 
the language. In it the origin of the world, of the earth and 
its inhabitants, is represented as the work of a personal 
Almighty God. The Jews were alone among the great nations 
of antiquity in realising the godhead as a unity all-powerful, 
all-embracing. The Mosaic account was incorporated in the 
Bible of the Christian Church, and, unfortunately, became 
invested with a scientific value by the Church. This retarded 
the development of geology for many centuries, inasmuch as 
theologians regarded the Mosaic account as a divine revelation, 
an essential dogma of the Christian Church, and sought to sup- 
press any investigations and writings of scientific interest which 
did not harmonise with it. 

While certain natural events, such as earthquakes, floods, 
and sometimes volcanic eruptions, recur in the primitive tradi- 
tions of the different nations, these cannot be regarded as 
affording a basis of geological facts; their interest is rather 
mythological and religious than scientific. 

The Greeks were less inclined than the Oriental nations to 
interweave the ideas of mythology, religion, and science; they 
viewed natural events from a more critical standpoint, and 
treated them as subjects of philosophical speculation. Various 
hypotheses were formed to explain the beginning of the earth. 


Hesiod's "Theogoriy" is the oldest of the Greek cosmogonies, 
but from what we know of it, the speculations of this early 
Greek philosopher were rather brilliant flights of fancy than 
efforts to assimilate observations of natural phenomena. 
Thus, the world is said to have taken origin from a primeval 
chaos, and to have given birth to the heavens, the mountains, 
and the oceans; then the races of gods sprang from the earth 
and the heavens. 

Thales of Miletus, the contemporary of Croesus and Cyrus, 
considered that everything, animate and inanimate, was derived 
from water. His gifted scholar, Anaximander (born circa 611 
B.C.), arrived at a higher conception of Nature. He depicted 
an infinite, all-pervading primeval substance, possessing an 
inherent power of movement from the first. The energy of 
this primeval matter determined heat and cold, and the mix- 
ture of these conditions gave origin to the development of 
fluid; the earth, the air, and a surrounding circle of fire 
differentiated from the fluid state. The stars sprang from fire 
and air; the earth rested in the centre of the whole universe, 
and under the influence of the sun brought forth the animals 
which inhabit it. These, including human beings, were at 
first fish-like in form, consistent with the semi-fluid state of 
their environment. Thus Anaximander had the merit of 
appreciating certain physical states as attributes of universal 
matter; his work, TTC/H <vo-eo>s, is unfortunately lost. 

Xenophanes of Colophon (born 614 B.C.) is reported by 
later writers to have observed the shell remains of pelagic 
mollusca on mountains in the middle of the land, impressions of 
laurel leaves in the rocks of Paros, as well as various evidences 
of the former presence of the sea on the ground of Malta, and 
to have attributed those appearances to periodic invasions of 
the sea during which men and their dwellings must have been 
submerged. The historian Xanthus of Sardis (circa 500 "B.C.) 
also drew attention to the occurrence of fossil shells in 
Armenia, Phrygia, and Lydia, far from the sea, and concluded 
that the localities where such remains occur had been for- 
merly the bed of the ocean, and that the limits of the dry 
land and the ocean were constantly undergoing change. 

Herodotus (born 484 B.C.) mentioned the presence of fossil 
shells of marine bivalves in the mountains of Egypt and near 
the oasis of Ammon. From this fact, as well as from the salt 
constitution of the rocks, Herodotus formed the opinion that 


Lower Egypt had been at one time covered by the sea, and 
that the material carried down by the Nile had been discharged 
into the sea-basin between Thebes and Memphis and the 
present delta, and gradually filled it up. Herodotus could not 
form any definite opinion as to the cause of the Nile inunda- 
tions, although he gave a careful report of the hypotheses then 
in favour. 

Heraclitus (born 535 B.C.) thought there was in the universe 
nothing stable, nothing lasting. Everything was in a state of 
constant change, like a stream in which new waves endlessly 
supplant the old. For him fire was the primeval force, which 
unceasingly transformed itself, pervaded every portion of the 
universe, produced individuals, and again destroyed them. 
Fire became the ocean, and that again earth, and the breath 
of life. The rising vapours burned in the air and formed the 
sun, which was renewed from day to day. Thus Heraclitus 
taught that although the universe always had been and always 
would be, no portion of it had ever been quiescent, and that 
from time to time a new world was constructed out of the 

Pythagoras, who was born at Samos about the year 582 B.C., 
and afterwards went to Crotona in Italy, is one of those 
eminent leaders of thought around whose name and teaching 
much that is mythical has gathered. The exponents of his 
teaching in subsequent ages too often attributed to the early 
Pythagoreans conceptions which were in reality foreign to the 
doctrines of the great master himself, and it is extremely 
difficult to disentangle the threads of original thought from the 
confused web of tradition. It is clear that the Pythagoreans 
indulged more in abstract speculation than their predecessors, 
and gave less attention to observation of nature. They sought 
to explain natural phenomena chiefly by analogy with definite 
numerical relationships. An ordered universe depended, 
according to the Pythagoreans, upon the principle of numbers. 
Consequently the properties of numbers, individually con- 
sidered, in sequence, and in combination, were investigated 
with a zeal which enabled the school to lay the foundation of 
important mathematical advances. In applying the principle 
of numbers to musical sound, Pythagoras is reputed to have 
arrived at a true conception of musical intervals and to have 
established the theory of the octave. On the other hand, the 
Pythagoreans were less happy in their application of the limita- 


tion of numbers to the physical problems of the universe, and 
lost themselves in forced analogies and conjecture regarding 
the "harmony of the spheres." According to Diogenes 
Laertius, Pythagoras imagined the universe in the form of a 
sphere. The earth was in the centre, and bore the axis around 
which the firmament revolved. The moon, the sun, Mercury, 
Venus, Mars, Jupiter, and Saturn described circular paths 
round the earth, and the harmonic motion of these bodies 
called forth the music of the spheres. The Pythagorean 
Philolaus improved on this conception. He described the 
universe as a system comprising ten heavenly bodies the five 
planets, the sun, the moon, the earth, and a counter-earth 
which moved from west to east round a " central-fire." The 
earth turned one half towards the central-fire, whilst the other, 
or inhabited half, received light and heat from the sun. 
Entirely beyond the circles of this system lay the fixed stars 
and the illimitable ether from which the universe drew its 

The principle of constant change taught by Pythagoras and 
Heraclitus is also a leading feature in the doctrines of 
Empedocles of Agrigentum (492-432 B.C.). Empedocles sup- 
posed that everything had its origin in, and took its components 
from, four elements (earth, water, air, and fire) ; that these 
elements were without beginning and imperishable, but subject 
to never-ending change. From these elements the world at 
one time took shape, and it must at some future time be again 
dispersed. The course of the world's existence resolved itself 
into a history of recurring periods and phases. As Empedocles 
did not concern himself about an empirical basis for most of 
his theories, it is of little avail to enter into his physical and 
biological speculations. Geology, however, owes one distinct 
step in advance to this philosopher. Whereas the Pythagoreans 
had conjectured the presence of a central fire in the universe, 
Empedocles taught that the earth's centre was composed of 
molten material. Empedocles formed this opinion on the basis 
of his actual observation of the volcanic activities of Mount 
Etna. Tradition says that he met his death by falling into the 
crater of that volcano. 

Leucippus and Democritus of Abdera (circa 490 B.C.) were 
the founders of the school of atomic philosophy, which of all 
the Greek systems approaches most nearly to the opinions of 
the present day. According to Democritus, the only realities 


are atoms; nothing that exists can be destroyed; change 
takes place in virtue of the combination or separation of 
atoms. Atoms are always in motion and are endless in 
number and variety; they move about in space; they 
press upon one another in every direction; they assume 
eddying movements which give origin to new worlds : but 
everything happens according to a definite sequence of law, and 
nothing by chance. Even the soul consists of very finely 
divided atoms which permeate the body and call forth the 
phenomena of life. 

In opposition to the materialistic view of the atomic philo- 
sophy, Anaxagoras of Clazomenae (bom 501 B.C.) regarded the 
soul (vovs) as in itself a conscious, moving force. In his cosmic 
philosophy he supposes an original chaos in which a circular 
movement gives place to a universe, and at the same time 
effects a differentiation of ether, air, and water. The earth 
rises from the water, and receives seeds from the air which 
develop into living plants and animals. The earth is poised 
as a cylinder in the centre of the whole universe, and the stars 
move round it. 

As the influence of the Sophists and Platonic philosophy 
came more into ascendency, it tended to elevate dialectic and 
speculative methods and to depreciate the investigation of 
natural phenomena. Cultivated and gifted as the Athenians 
of this epoch were, natural science owes but a small debt to 

Plato (427 B.C.), in his Cosmology, is a follower partly of 
Heraclitus and partly of Anaxagoras. According to Plato, the 
universe is the production of divine intelligence and of the 
necessary development of nature. The form of the whole 
universe is spherical ; in the centre lies the earth as a motion- 
less sphere; around it are the sun and the planets, and the 
fixed stars occupy the outermost circle. All the heavenly 
bodies are inhabited; the atoms composing them are indivisible, 
and unite along definite limiting surfaces ; the universe itself is 
unchangeable and indestructible. 

An interesting account is given in the "Tirnasus" of a 
submerged Atlantic continent (Atlantis) on the other side of 
the Pillars of Hercules (Gibraltar). The idea of such a sub- 
merged continent has again received credence in recent geo- 
logical researches. In Plato's account Atlantis was larger than 
Asia and Libya together, it had been inhabited 9000 years 


before his time, and since its destruction by earthquakes and 
inundations navigation in the Atlantic had been impossible 
owing to the fine mud and detritus left by the vanished land. 

The work of Aristotle (384-322 B c.) marks the culminating 
point reached by the Greeks, both in the domain of speculative 
philosophy and in that of empirical observation. Although 
the physical and geological researches of the great Stagirite 
embrace less of original discovery than his researches in 
zoology and physiology, they group and define more precisely 
the best results of the Eleatic, Pythagorean, and Atomic 
philosophers, re-animate them with new thoughts, and fre- 
quently place them on a true scientific basis. Aristotle departs 
from the atomic philosophers in assuming that matter is diverse 
in quality, and that the universe is divided into an earthly and 
a heavenly half; the imperishable ether belongs to the heavenly 
half, while the four elements, earth, water, air, and fire, com- 
pose the earth and the planets. The earth forms, in Aristotle's 
conception, the stationary centre of the universe round which 
the planets move to the left ; beyond their orbits is the great 
ethereal circle of the heavens in which the stars move towards 
the right. The development of the earth is comparable with 
that of an organism ; it has periods of growth, maturity, and 
decay. During recurring periods of rejuvenescence the lower 
animals take origin in the mud of the earth, and from them 
develop, by sexual generation, the higher groups of animals. 
The plants are related to animals, and the different kinds of 
animals to one another by numerous transitional forms. Aris- 
totle's works seldom treat special geological questions, and his 
meteorology, although it discusses earthquakes, the alternation 
of continent and ocean, the Deucalion flood and inundations 
of the Nile, does not contribute much that is new. 

Theophrastus of Lesbos (368-284 B.C.), the most famous 
pupil of Aristotle, devoted himself chiefly to scientific studies. 
In addition to his valuable botanical treatises, he gave much 
information about minerals and fossils in a fragmentary treatise 
" On Stones." A special work on fossils, with which Pliny 
was apparently acquainted, has since been lost. 

The Encyclopaedists of the Alexandrine school occupied 
themselves chiefly with astronomy, mathematics, and geo- 
graphy. Eratosthenes (276-196 B.C.) by his measurement of 
the degree in Egypt for the first time laid the foundation 
of a more exact estimate of the size of our planet. He 


also gave expression to various hypotheses regarding the 
relationship of mountain-chains, the action of water, and the 
presence of the ocean above the continent, as indicated 
by the occurrence of oysters and other marine organisms 
in the Libyan deserts on the way to the oasis of Ammon. 
Eratosthenes taught that the changes of form accomplished 
by means of water, by volcanoes and earthquakes, and by 
fluctuations of the sea, are insignificant in proportion to the 
size of the whole earth. *4 

Thus it will be seen that the majority of the older Hellenic 
philosophers gave their attention to speculative considerations 
on the origin of the universe and the earth ; but under 
the manifold activities of the Roman empire, a new and 
more realistic spirit became infused into the investigations 
of the great thinkers. Amongst these the first place must 
be given to the historian and traveller Strabo (born circa 
63 B.C.), whose geography, comprising seventeen volumes, 
was written about the beginning of the reign of Tiberius. 
Strabo had a thorough mastery of the Greek literature, and in 
reference to the occurrence of the above-mentioned fossils in 
the Libyan desert, he agreed with the Greek philosophers that 
the sea had once covered certain portions of the land, but he 
also pointed out that the same district may sometimes rise, some- 
times sink, and fluctuations of the sea-level are associated with 
such movements of land-surfaces. He further taught that eleva- 
tions and subsidences of the land are not confined to indi- 
vidual rocks or islands, but may affect whole continents ; that 
Sicily, Procida, Capri, Leucosia, the Sirenian and (Enotrian 
islands had been separated from Italy by earthquakes, and 
that probably all islands off the shores of continents had origin- 
ally formed part of the mainland. The oceanic islands far from 
any mainland have, according to Strabo, been thrown up by 
subterranean fires. In support of this view Strabo cited the 
case of a volcanic eruption in the year 196 B.C. between 
Thera and Therasia. For four days flames rose from the ocean, 
and as these died down it was observed that a new island 
had been formed, measuring twelve stadia in circumference. 
Again, near Methone in the Hermionian Sea, a mountain, 
seven stadia high, had been thrown up during outbursts of 
sulphurous vapours and fire; and the town of Spina, near 
Ravenna, formerly a seaport, was now ninety stadia inland. 
Strabo is therefore rightly regarded as the father of modern 


theories of mountain-making, and we owe to him, moreover, 
the hypothesis that volcanic outbursts act as safety-valves for 
the pent-up activities of subterranean vapours. He pointed out, 
that Sicily in his time was less frequently disturbed by earth- 
quakes than it had been in previous ages before volcanic 
discharges were known in the district, and he correlated the 
comparative tranquillity of the ground with the means of 
escape afforded for explosive underground vapours by the 
volcanic vents that had opened at Etna, in the Lipari Isles, and 
in Ischia. It speaks highly for Strabo's powers of observation 
that he should have recognised in Vesuvius a volcanic moun- 
tain although it was then quiescent. 

Probably the most acute scientific observer of Roman times 
was Seneca, the physician of the Emperor Nero (born 2 or 4 
B.C., died 65 A.D.). Quite recently, Nehring has placed 
the importance of the work of Seneca in its true light. The 
Qucestiones Naturales contain detailed communications about 
earthquakes, volcanoes, and the constructive and destructive 
agencies of water. Seneca explains earthquakes partly as a 
result of the expansion of gases accumulated in the earth, 
partly by the collapse of subterranean cavities. He regards 
volcanic eruptions simply as an intensified form of the same 
series of phenomena, and volcanoes themselves as canals or 
vents between local sub-terrestrial reservoirs of molten material 
and the earth's surface. He names the chief volcanoes, 
placing Etna in the first rank ; then Stromboli, Therasia, and 
Thera (the present "Santorin"), but there is no mention of 
Vesuvius. He regards the earth as primitively a watery chaps, 
and it is more especially in his treatment of the action of water 
in dissolving and carrying away rock-material, together with 
his explanation of the origin of sediments and deltas, that 
Seneca has shown his remarkable insight and sound judg- 

The learned historian, Pliny the Elder (23-79 A.D.), has 
handed down to us a compendium that embraces the whole 
scientific knowledge of antiquity. His Historia Naluralis^ in 
thirty-seven books, embraces the natural history of animals, 
plants, and stones, the history of the heavens and the earth, 
of medicine, of commerce, of navigation, etc.; in Lib.. II., 
c. 88 and 89, all the islands that have been thrown up in the 
ocean are enumerated Delos, Rhodes, Anaphe, Nea, Alone, 
Thera, Therasia, Hiera, Automate, and Thia. The reports 


about volcanoes, earthquakes, and fossils, occurring here and 
there in this work, are not always trustworthy. They seem, 
in most cases, to have been based on indirect informa- 
tion. By a tragic decree of fate, the untiring student and 
naturalist met his death while engaged in observing the 
grandest geological event of antiquity, the first outbreak of 
Vesuvius in the year 79 A.D. Pliny the Younger describes the 
death of his uncle in two letters to Tacitus, recounting how 
at the beginning of the eruption the elder Pliny was stationed 
at Misenum as Commander of the Fleet, but went at once to 
Stabia to bring help to the sufferers and to witness the great 
drama of nature. He died in the open field, probably suffo- 
cated by the volcanic vapour and ash. His corpse was found 
unharmed three days later, when the darkened sky gradually 
became clear. The younger Pliny's vivid description of the 
eruption of Mount Vesuvius, and the accompanying earth- 
quake, is one of the most remarkable literary productions in 
the domain of geology. It is certainly curious that he should 
have omitted to mention the earth-tremors at Herculaneum, 
Pompeii, and Stabia, confirmation of which has however been 
given by Dio Cassius. 

A poetic account of an eruption of Mount Etna is happily 
amongst the fragments that have been preserved from the 
works of Lucilius, the poet in the second century A.D. Alto- 
gether this volcano played a very important role in the litera- 
ture of the ancient writers. Nor were the Romans devoid 
of interest in fossils : Suetonius relates that the Emperor 
Augustus decorated his villa in Capri with huge fossil bones, 
which at that time were held to be the remains of a giant 

If we pass in review what antiquity has bequeathed to us of 
actual geological knowledge, we find our heritage surprisingly 
meagre. The tendency of eastern races towards the fanciful, 
and of the Greeks to philosophical speculations, brought forth 
an abundance of hypotheses about the origin of the universe 
and the development of the earth; and even although some of 
these may in part coincide with accepted scientific conceptions 
of the present day, it has to be remembered that in these 
cases the early hypotheses were rather happy "guesses at 
truth," than general theories founded inductively upon a series 
of accurately observed data. 

Far more valuable than the most ingenious speculations are 


the occasional remarks and observations about volcanoes, 
earthquakes, fluctuations of level in the land-surfaces, the 
action of water, and other phenomena of dynamic geology, as 
well as the scattered notes about the occurrence of fossils. 
On the other hand, not a single writer of the ancient world 
showed any interest in the firm earth-crust, not one observer 
gave a thought to the composition of the rocks. Not the 
most acute thinker of those cultured peoples had even a 
shadowy premonition of the value that might appertain to 
fossils as witnesses of a sequence of events in the history of 
our earth. None suggested that our planet might have passed 
through a succession of changes before attaining to its present 
physical condition and configuration ; still less, that particular 
phases in the history of change might be deciphered from the 
character and superposition of the rocks. The evolution of 
the earth and its denizens, which is at the present day the 
great problem of geological and biological research, played no 
part in the literature of antiquity; fanciful hypotheses and dis- 
connected observations cannot be acknowledged as scientific 
beginnings of research. 


The downfall of the Roman Empire dealt a severe blow to 
literary progress and healthful interest in natural phenomena. 
The collapse of imperial power, the revolutionary instincts and 
unrest, the variable migration of the races, the protracted 
struggle between decaying heathendom and rising Christianity, 
the personal wars of jealousy and greed in which Europe was 
plunged during the greater part of the Middle Ages, all 
combined to check any spontaneous desire towards scientific 

A barren scholasticism took refuge in the monasteries and 
cloister schools. The attitude of the Schoolmen, while it 
made much of logical distinctions and the critical interpreta- 
tion of old doctrines, was unfavourable to the direct observation 
of nature. For many centuries (800-1300 A.D.) the Arabs were 
the only nation in which the true spirit of ancient culture and 
inquiry was kept alive. At great sacrifice they obtained 
possession of the classical works of antiquity, translated them 



into Arabic; and the Caliphs, Al Mansur, Harun-al-Raschid, 
and Al Mamun, endeavoured to attract to their courts the best 
scholars of all countries. Thus they handed down to posterity 
many of the most valued treasures of ancient learning, and 
they appreciably contributed to the knowledge of mathematics, 
astronomy, alchemy, medicine, and zoology. Geology and 
palaeontology, however, the kindred studies of the rocks and 
their fossil contents, were almost neglected by them. 

It was not until the close of the Middle Ages, in the fifteenth 
century, that a revival of learning spread through Europe. The 
discovery of the art of printing brought books within the reach 
of many. The keen interest in classical authors displayed 
by the leaders of the Humanist movement infused new life 
and activity into mental effort in every branch of knowledge. 
Universities, learned societies, and academies were founded. 1 
The methods of dogmatism were cast aside with the decay of 
scholasticism. Copernicus the Prussian (1473-1543) absorbed 
the best learning that Italy could give him, and rewarded the 
care of his foster-country by unfolding to futurity the system 
of the universe that bears his name. The Reformation gave 
an impulse to all men to think for themselves, and no longer 
to accept blindly the traditions of past ages. Columbus, 
Vasco da Gama, and other bold navigators added the Western 
Hemisphere to the former domain of geographical knowledge. 
And if less imposing, still no less certain, was the steady 
advance made in natural science under the influence of the 
healthier tone that prevailed. Men turned in earnest from 

1 Italy led the way in founding academies during the era of the Renais- 
sance of literature and research. The "Platonic Academy" was the name 
given to a group of learned men who were under the patronage of Cosmo 
di Medici, in Florence; but this society had no definite organisation. The 
Academy in Padua, founded in 1520, must therefore be regarded as the 
oldest scientific society, although it was not long in existence. In 1560 
an Academy of Natural Science was founded at Naples, and in 1590 the 
Academy dei Lincei in Rome was founded by the Marcese de Monticelli. 
It was not until the middle of the seventeenth century that the scientific 
academies of France, England, and Germany came into existence; then 
were established the Academic Fran9aise in 1633, the Royal Society of 
London in 1645 (established in 1662 with incorporated rights), the 
Academic des Sciences in Paris in 1666, and the Akademie der Wissen- 
schaften in Berlin in 1700. In 1725, Empress Catherine founded the 
Academy in St. Petersburg, and in the same year the Royal Society of 
Sciences was formed in Upsala. Since that time scientific societies have 
been founded in most of the large university towns. 


the desultory literary method of treating nature, to the more 
direct, more exacting system of observation and description. 
Plants, animals, and rocks were studied with enthusiasm, were 
examined, described, figured, and classified, so that in a rela- 
tively short space of time a fairly extensive botanical, zoological, 
and mineralogical literature sprang into existence. 

Various Opinions about Fossils. The Greek and Roman 
writers had correctly realised that fossils represented the 
remains of animals and plants, and most of the ancient writers 
had explained their preservation in the rocks as the result of 
great natural catastrophes which had changed the localities of 
land and water, and brought the swarming denizens of the sea 
into the middle of continents, burying them there. During the 
mediaeval Scholasticism no progress was made in the study of 
fossils. Avicenna (980-1037), the Arabian translator and com- 
mentator of Aristotle, became imbued with Aristotle's theory of 
the self-generation of living organisms, and tried to extend it to 
the case of fossils. Avicenna suggested that fossils had been 
brought forth in the bowels of the earth by virtue of that 
creative force (vis plasticd) of nature which had continually 
striven to produce the organic out of the inorganic, and that 
fossils were unsuccessful attempts of nature, the form having 
been produced but no animal life bestowed. 

The famous Albertus Magnus 1 takes the same standpoint 
more than two hundred years later. He assumes a virtus 
formativa in the earth as the origin of fossils, although he 
allows that the remains of plants and animals may be turned to 
stone in places where agencies of petrefaction are at work. 

With the dawn of the fifteenth century began that long series 
of disputes about fossils which lasted more than three centuries. 
The questions under discussion were, whether fossil organisms 
had taken origin from a vis plastica^ or from living seeds carried 
in vapours from the sea, or from any living force in the earth 
itself; whether they might be regarded merely as illusory sports 

1 Albert von Bollstsedt, called Albertus Magnus, was born at Laningen 
in Swabia in 1193; studied at Padua and Bologna, took Dominican orders 
in 1222, lectured for several years in the cloister schools of Cologne, 
Ilildesheim, Freiburg, and Regensburg, and taught in Paris between the 
years 1245-48. He returned then to preside over the High School at 
Cologne, and was made Bishop of Regensburg in 1260. This post he 
resigned after two years, and devoted himself, at Cologne, to his works on 
philosophical and theological themes until his death in 1280. 


of nature, or as mineral forms, or if they really were the 
remains of animals and plants that had once lived, and had 
been brought by the Flood or some other catastrophe into their 
present position. 

The world-famed artist and architect, Leonardo da Vinci 
(1452-1519), took part in the discussion. He had in his youth 
been engaged as an engineer in the construction of canals in 
North Italy, and had then seen numerous fossils in position 
in the rocks. The opinions he formed regarding them are 
remarkable for their clearness and correctness. Leonardo said 
that the marine organisms scattered in the earth in the form of 
fossils had actually lived where we now find them. The sea at 
that time covered the mountains of North Italy: the river-mud 
brought to the sea from Alpine lands filled the shells of dead 
mussels or snails, and accumulated on the sea-floor; afterwards 
the mud deposits became dry land, and the fossils found in 
them were the casts of the ancient cells. He ridiculed, as 
absurd and unscientific, the idea that such perfect models of 
living organisms could have taken origin in the rocks under 
hypothetical creative influences of the stars. 

The Neapolitan, Alessandro degli Alessandri (1461-1523), 
mentions petrified conchylia in the Calabrian mountains, and 
ascribes their presence to an inundation of the continent by 
the ocean, caused by some exceptional catastrophe, or by a 
change in the axis of rotation of the earth. 

Fracastoro, 1 in the year 1517, gave clear expression to his 
convictions about fossils, which were in accordance with those 
of Leonardo da Vinci. During the building of the citadel of 
San Felice in Verona, the workers found fossil mussels in the 
rocks and laid them before Fracastoro, begging him to explain 
the marvel. Fracastoro repudiated the doctrine of a vis plastica 
in the earth as impossible; and just as little did he give 
credence to the view that explained fossils as creatures left by 
the great Flood. The Flood, he said, was of short duration, 
and in the nature of things it would have left not marine but 
fresh-water mussels behind; further, on the assumption that 
the mussels had been carried from the ocean to the land by the 
Flood, their remains would have been scattered over the 

1 Hieronymus Fracastoro, born at Verona in 1483, studied at Padua, 
and became Professor of Philosophy there in 1502; afterwards practised 
medicine as a physician in Verona, and in his capacity of physician to Pope 
Paul III. was a member of the Council of Trent. He died in 1553. 


surface of the land, and would not have been buried deep in 
the earth where the quarrymen had found them. There was 
left, he continued, only one possible explanation that the 
fossils were the remains of animals which had once lived in the 
localities where their remains are now imbedded. 

Far more illustrious than the majority of his contemporaries 
in science was George Bauer, 1 better known by his nom-de- 
plume of Agricola. Werner calls him the father of metallurgy, 
and the originator of the critical study of minerals. Bauer's stay 
in Joachimsthal enabled him to become familiar with the mines 
there, and to make a collection of local minerals. The clever 
physician soon received general recognition as the best 
authority on mining, and the publication of his pamphlet 
" Bermannus " in 1528 further confirmed the prominent 
position he held among mineralogists. His great work, De re 
metallica libri duodedm^ contains a complete description of 
mining and metallurgy as then practised, as well as valuable 
communications about the mode of occurrence of useful 
minerals, and about veins and deposits of ore. Two later 
works, De natura fossilium^ Lib. x., and De veferibus et novis 
metallis, Lib. ii., describe all the minerals known to the ancients, 
and all those which had since been discovered. Agricola's 
observations on crystalline form, cleavage, hardness, weight, 
colour, lustre, etc., have served as a model for all subsequent 
descriptions of minerals. On the other hand, Agricola's 
remarks about fossils are of much less value. He had devoted 
little attention to the fossil remains of animals and plants, and ' 
he unfortunately united under the name " Fossilia " both 
minerals and petrified organisms. This use of 'the term 
" Fossils " was perpetuated for two centuries in the literature, 
having been more especially adopted by the famous Wernerian 
School. Agricola referred by far the greater part of the organic 
remains found in the solid rock to a wholly inorganic origin; 
he regarded fossil mussels, belemnites, "Ammon's Horns," 
" Glossopetra " (fish teeth), and other problematical remains as 

1 Georg Bauer (Agricola) was born at Glauchau in Saxony in 1494. lie 
went to Italy, where he graduated as doctor, and then settled in Joachims- 
thai as a physician; afterwards he was appointed professor of chemistry at 
Chemnitz, and died there 1555. A complete edition of his works was 
published in the Latin tongue in Bale. A German translation of the 
mineralogical writings was published at Freiburg in 1816 by Ernst 


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I In- mlhiriK r nl ihc slats. 

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th,- , i l,i, , nili , eiilmy, so many anlhoi ; < Inn:- Io sin h .il-Mnd 
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means of good illustrations to an ever-increasing number of 
observers. The works of Aldrovandi, Athanasius Kircher the 
Jesuit, Sebastian Kirchmaier, Alberti, Balbini, Geyer, Hartley, 
and many others in the seventeenth century contain some very 
good figures, and extended the knowledge of the fossils 
found in various European localities. The fossils were, 
however, treated usually as mineral curiosities, or as illusions 
of nature, sometimes as forms called forth in the earth by 
vis plastica or some other force, sometimes compared with 
living mussels, snails, sea-urchins, plants, etc., and named 

Probably the greatest representatives of this literature are 
the Englishmen Lister and Lhuyd (Luidius) and the Swiss 
Nikolaus Lang. Martin Lister 1 had an excellent knowledge 
of living conchylia. He had also observed that certain rocks 
are present over a definite extent of surface, so that maps might 
be constructed with respect to the distribution of different 
kinds of rock, and further, that the fossil bivalves and snails 
differed in the different kinds of rock. He therefore laid 
down the important principle that the different rocks might 
be distinguished according to their particular fossil contents, 
although, strange to say, he thought the rocks themselves had 
the power to produce the different forms of fossils. Lister 
warmly combated the idea that the fossils could have proceeded 
from animals (Philos. Trans. Roy. Soc. London, 1671). Never- 
theless, he illustrated living and fossil conchylia side by side 
with one another, in order to demonstrate their resemblance, 
at the same time writing in the text, that the fossil conchylia 
were mere rough imitations of the real forms imitations 
produced in the rocks by some unknown causes. 

The English antiquary, Edward Lhuyd (Luidius), described 
a thousand species of British fossils in a long and beautifully 
illustrated work. Lhuyd's theory of " Aura seminalis " strongly 
recalls the fanciful doctrines of Anaximander and Theophrastus. 
In a letter, "De fossilium et foliorum mineralium origine," to the 
famous zoologist John Ray, Lhuyd sets forth how the fossils 
have developed from moist seed-bearing vapours which have 
risen from the seas and entered into the strata of the earth. 

1 Lister was born at Radcliff in 1638, studied in Cambridge, and was 
highly respected in York and London as a medical man. In 1698 he 
accompanied the English ambassador, Lord Portland, to Paris, in 1709 
became house physician to Queen Anne, and died 1711. 



Lhuyd found an enthusiastic supporter in the Lucerne 
physician and councillor, Karl Nikolaus Lang, whose Historia 
lapidum figuratorum Helvetice (Venice, 1708) contains 163 
plates, with a number of good figures of fossils. Lang is one 
of the last authors who believed in the direct origin of the 
fossils in the rocks. 

A semi-tragic, semi-comic event brought this literature to a 
close. Johannes Bartholomew Beringer, a professor in the 
University of Wiirzburg, published in 1726 a palreontological 
work entitled Lithographia Wurcebitrgensis. In it a number 
of true fossils were illustrated, belonging to the Muschelkalk or 
Middle Trias of North Bavaria, and beside these were more or 
less remarkable forms, even sun, moon, stars, and Hebraic 
letters, said to be fossils, and described and illustrated as such 
by the professor. As a matter of fact, his students, who no 
longer believed in the Greek myth of self-generation in the 
rocks, had placed artificially-concocted forms in the earth, and 
during excursions had inveigled the credulous professor to 
those particular spots and discovered them ! But when at 
last Beringer's own name was found apparently in fossil form 
in the rocks, the mystery was revealed to the unfortunate 
professor. He tried to buy up and destroy his published 
work; but in 1767 a new edition of the work was published, 
and the book is preserved as a scientific curiosity. Many 
of the false fossils (Liigensteine) may be seen in the 
mineral collections at Bamberg, and there are also speci- 
mens in the university collections of Wiirzburg, Munich, 
and other places. 

Contemporaneously with these mistaken efforts in the 
sixteenth, seventeenth, and early part of the eighteenth 
century, a truer appreciation of fossils was gaining ground. 

In the year 1580, the famous French worker in enamel, 
Bernard Palissy, published a book in which he discussed the 
origin of petrified wood, the occurrence of fossil fishes in 
Mansfield slate, and fossil molluscs in various rocks. 
Palissy rightly pointed out that many of the fossil conchylia 
were identical with living species, and said they must have 
developed in localities which had previously been under fresh 
or sea- water. Palissy's ideas were violently attacked by his 
compatriots, and he was denounced as a heretic in his 
philosophical and scientific writings, just as he was a 
Huguenot and a heretic in his religion. 


Fabio Colonna l upheld similar views in Italy. He tried to 
show that the " Glossopetren" were not tongues of serpents but 
the teeth of dog-fish, which occurred along with remains 
of marine bivalves and snails in certain strata ; while in 
others he recognised the remains of terrestrial animals and 

During the seventeenth century Nikolaus Steno and other! 
Continental geologists contested the erroneous and ludicrous 
ideas of their contemporaries ; while in England, Robert 
Hooke, John Ray, and John Woodward guided scientific 
thought to the true explanation of fossil remains. Leibnitz, 
the founder of the Academy of Science in Berlin, and 
Scheuchzer, the Swiss geologist, further advanced the scientific 
research of fossils, so that, by the middle of the eighteenth 
century, no man of science and letters believed that fossils 
might be products of the earth itself. 

The English physicist and mathematician, Robert Hooke 
(1635-1703), was one of the most brilliant original thinkers 
of his own or any age. It was he who for the first time } 
suggested the use that might be made of fossils, in 
revealing the historical past of the earth. In an important ' 
work upon earthquakes written in i688, 2 he stated that fossil 
molluscs deserved to be regarded as historical, since they 
represented monuments no less valuable than coins and 
manuscripts, but he added that it certainly would be ex- 
tremely difficult to construct a chronology of the earth upon 
the evidence of fossils. Many fossil Ammonites, Nautilids, 
and other conchylia undoubtedly differed from known living 
forms, but he said it had to be remembered how scanty was 
the existing knowledge of marine animals, especially of those 
which inhabited the greater ocean depths. Hooke, however, 
inclined to the opinion that the fossils of unknown forms 
might really be extinct species, annihilated by earthquakes.. 
He regarded it as certain that a number of fossil species had! 
been confined to definite localities. And from the occurrence 
of fossil Chelonias and large Ammonites in the strata of . 
Portland Isle, Hooke concluded that the climate of England ) 
had once been much warmer. This was explicable, in 
Hooke's opinion, upon the assumption either that the earth's 

1 Osservazioni siigli animali aqnatici e terrtstri, 1616. 

2 This treatise is published in the Opera posthuma Robert Hooke, ed. 
Rich. Waller, London, 1705. 


j axis of rotation or the earth's centre of gravity had undergone 
] changes of position. 

Hooke further gave some valuable hints about the alteration 
of organic remains by the process of petrefaction, and cited as 
examples the petrified stems of trees in Africa and in the 
kingdom of Ava. His explanation of the elevated position in 
which fossil marine organisms are now found was based upon 
his theory of earthquakes. Earthquakes, he thought, trans- 
formed plains into mountains, and continents into ocean 
basins. He attributed earthquakes and volcanic eruptions to 
the agency of subterranean fire. 

Scarcely had the organic origin and historical significance of 
fossils been successfully vindicated, than the doctrinal in- 
fluences of the day stepped in and claimed all fossil forms as 
vestiges from the earlier creation interred in the earth during 
the great Deluge. The " Diluvialfcts" formed a powerful party 
amongst the geologists of the seventeenth and eighteenth 
centuries, and were warmly supported by the Church. In 
England, Woodward, Burnet, and Whiston had strong 
convictions in this direction; while in Germany, Wedel 
and Baier, and in Switzerland Johann Scheuchzer, taught 
that all fossils had been spread through Europe during the 

Scheuchzer had in his first work {Specimen Lithogr. 
Helvetica Curioscz^ 1702) regarded fossils as sports of nature, 
but under the influence of Woodward's work, which he 
translated into Latin, he became an enthusiastic believer in 
the theory of a diluvial distribution of fossils. His natural 
history of Switzerland contains a special chapter, which 
professes to deal with the fossil remains left by the Flood in 
Switzerland. Towards the close of his life, Scheuchzer 
thought he had discovered in the beds of Oeningen "the bony 
skeleton of one of these infamous men whose sins brought 
upon the world the dire misfortune of the deluge." But the 
supposed homo dtluviihom Oeningen was afterwards determined 
by Cuvier to have been a gigantic Salamander, and was called 
Andrias Scheuchzeri in honour of its Swiss discoverer. The 
original specimen of Scheuchzer's Andrias is now in the^ 
Teyler Museum at Haarlem. 

The strong personality of Scheuchzer and his success as a 
teacher won for him during his life-time a large circle of 
scientific supporters, and contributed not a little to a more 


general interest in fossils. Numerous books and treatises 
began to appear, sometimes describing the fossils in particular 
localities, sometimes of a more dilettante character. 

In Switzerland, Johann Gesner's work continued the lines of 
research initiated by Scheuchzer. Bourguet in Neuchatel, and 
afterwards Burtin in Belgium, published handsome plates of 
fossil illustrations, but the descriptions in the text are not of 
much value. Johann Baier, the Altdorf Professor, published 
in 1712 his Oryctographica Norica, one of the best works of 
the time, and in 1757 a supplement of fifteen folio plates was 
added under the direction of his son P'erdinand. 

France, until the middle of the eighteenth century, had 
a remarkably poor palseontological literature. Antoine del 
Jussieu in 1718 described the Carboniferous plants of St.j 
Chamont, near St. Etienne, and said they had been brought by I 
the flood from India and the New World to Europe. In a 
second treatise, Jussieu described fossil Ammonites; he 
certainly compared these with Nautilius Pompilius of the 
Indian Seas, but he explained them as having been brought 
from the Oasis of Ammon to France by inundations of the 
sea. Bertrand's Dictionary of Fossils and other minor 
works testify that France was not devoid of interest in fossils, 
although activity in this field of research was much more 
prolific in the neighbouring countries. 

In France, during the eighteenth century, only the writings 
of Guettard can be placed in the same rank with the 
monographs of particular fossil groups prepared by Rosinus, 
Wagner, Erhart, Breyn, and Klein. 

The outstanding work of this period is undoubtedly that of 
Knorr and Walch in four volumes, Die Sammlung von 
Merkwilrdigkeiten der Natur und Alterthumer des Erdbodens. 
The first volume was written by the Niirnberg collector and 
artist, George Wolfgang Knorr (born 1705, died 1761), and 
the other three volumes were prepared after the death of 
Knorr by Professor Walch 1 of Jena. 

The first volume bears on its title-page an illustration of the 
famous Solenhofen quarries, and contains figures of fossil crabs, 
fishes, crinoids, together with dendrites, and "ruin marble" 

1 Johann Ernst Immanuel Walch (1725-78) was a son of J. G. 
Walch, Professor of Philosophy and Poetry in Jena. In 1759 Walch 
succeeded his father as Professor, but his chief delight was in Mineralogy 
and Palaeontology, and he made a famous collection. 


found in the calcareous slates and flagstones of Solenhofen. 
The first half of the second volume contains illustrations of 
molluscs, brachiopods, and echinids, and the descriptive text 
by Walch embraces practically all that was known in the 
previous literature about these fossils ; in the second half the 
same treatment is given to so-called " corallioliths " (sponges 
and corals), to encrinites (crinoids), to osteoliths (fossil 
bones), to belemnites, dentalites, vermiculites, and balanoids. 

The third volume begins with a dissertation about fossil 
wood, followed by the description of a number of Carbon- 
iferous plants. The chapter on the fossil Crustaceans which 
received the name of "Trilobites" from Walch, ranks far 
above all previous descriptions of these interesting fossils. 
The remainder of this volume is devoted to the description 
of supplementary plates. The fourth volume contains a 
systematic summary of all fossil forms treated in the 
foregoing volumes. The masterly text of Walch sets forth 
his own original observations, and displays a knowledge 
of the older literature unsurpassed for its completeness and 

With the exception of Knorr and Walch's important work, 
palgeontographical literature up to the middle of the eighteenth 
century stands on a low scientific level. This seems the more 
remarkable when one compares the formal descriptions of 
fossils, and speculations about their origin and their scrip- 
tural significance, with the well-directed efforts of botanists 
during the same period. Botanists had already brought the 
systematic arrangement of plants to such a point that only 
the nomenclature of Linnaeus was required to make it serve 
as a secure basis for the further progress of research. But so 
far, in the kindred study of the history and classification of 
animals, no fundamental principles had been attained. It 
is true some of the more advanced writers, such as Hooke, 
had said that certain fossil species might possibly be extinct 
forms. Yet, when from time to time ammonites, trilobites, 
crinoids, and other fossils were found which had no known 
existing counterparts, the authorised treatment was to take for 
granted there might be living representatives existing at depths 
or in regions of the ocean hitherto unexplored. 

Interest centred in the chimeric hope of finding living 
specimens of these mysterious fossils, and no observer had yet 
conceived the far bolder, grander dream of defining successive 


periods of the earth's history by means of an ordered array of 
extinct fossil forms. 

Hypotheses of the Earth's Origin and history, and 
Beginnings of Geological Observation. The ^een interest in 
minerals and fossils and the flourishing condition of the 
mining industry gradually attracted the attention of scientific 
men to the investigation of the earth itself. Two methods 
of research, the empirical and the speculative, developed 
alongside one another. The one had for its immediate aim 
the determination of facts, and in its further outlook, the 
possible construction of some suitable theory ; the other 
contented itself with a minimum of observation, accepted the 
risks of error, and set about explaining the past and the 
present from the subjective standpoint. This latter method 
naturally attained no higher results than the geogenetic 
fantasies of classical antiquity. And it certainly could never 
have gathered sufficient energy to roll aside the mass of 
philosophical and doctrinal tradition that blocked the path of 

Throughout the later and Middle Ages, water and fire still 
continued to be accepted as the two essential active and 
formative forces dominating the earth's configuration, hence 
it was unavoidable that the conceptions of the ancient philo- 
sophers should re-appear again and again in the newer theories, 
if in renovated form. Meantime there were in every land of 
Europe empiricists who were patiently contributing new data 
to the knowledge of chemistry, of physics, and the constitu- 
tion of the earth's crust, and were thus preparing the only 
possible foundation of a science of geology. 

Leonardo da Vinci deserves an honoured place amongst the 
founders of geology, as one of the first who investigated the 
earth's structure upon scientific principles. Not only did 
Da Vinci recognise the true origin of fossils, but his artistic 
sense of form and his close observation of nature revealed to 
him in the North Italian valleys the agency of running water 
in sculpturing the earth's surface. He showed how rivers erode 
their valleys, and deposit pebbles on valley terraces; how a 
fine detritus accumulates at river mouths, and plants and 
animals are buried in it ; how the organic remains then pass 
through physical changes and become petrified while the 
river mud hardens into solid rock, and finally the rock 


containing the imbedded fossils rises above sea-level and 
becomes dry land. 

Agricola, the mineralogist, also made a number of useful 
observations about springs, earthquakes, active and extinct 
volcanoes, volcanic rocks, the action of running water, and 
atmospheric movements. 

Giordano Bruno, who was burnt at Rome in 1600 for heresy, 
was a natural philosopher of considerable insight. A reprint 
of his ideas appeared quite recently (Boll. Soc. Natur. Napoli, 
1895). Bruno described the earth as a spherical body, on 
whose surface the depths of the oceans were greater than the 
height of the mountains; the mountains were no higher in 
proportion to the size of the earth than the wrinkles on the 
skin of a dried apple. Bruno also denied that there had ever 
been a universal Deluge, but brought forward evidences of 
frequent alteration in the distribution of land and sea. He 
also directed attention to the position of volcanoes in the 
immediate proximity of the sea, and from that he argued 
that thermal and volcanic phenomena might be due to some 
interaction between surface waters and the interior of the 
earth. Bruno's ideas were not understood by his contempor- 
aries and were neglected. 

No writer was more appreciated in his time than the 
accomplished Jesuit, Athanasius Kircher. 1 His famous work, 
Mundus subterraneiiS) begins with the consideration of the 
centre of gravity of the earth, and the form and constitution 
of sun, moon, and earth. Book III. is devoted to hydro- 
graphy, another book (Pyrologus) treats of the earth's interior, 
volcanoes, and winds. Kircher's idea is that there are in- 
numerable subterranean centres of conflagration (pyrophylada}., 
which are connected with active volcanoes ; similarly that 
there are special water cavities in the earth (Jiydrophylacia), 
which are fed from the sea and are connected by branches 

1 Athanasius Kircher was born 2nd May 1602, at Geisa, near Eisenach, 
and died 1680, in Rome ; was educated in the Jesuit College of Fulda, and 
took orders in 1618 at Paderborn. He was an accomplished linguist, and 
travelled through Sicily, Malta, and the Lipari Islands, visiting Etna, 
Stromboli, and Vesuvius. He was made a Professor in Wurzburg in 1630, 
but on the approach of the Swedes in 1633, took flight to Avignon, and 
afterwards accepted the post of teacher of Mathematics in the Collegium 
Romanum in Rome. There he founded a valuable natural history collec- 
tion, which was afterwards described by Bonanni in 1709 under the name 
of Museum Kircherianum, and is still kept up in Rome. 


in all directions with the earth's surface, at which they appear 
as thermal springs. Kircher follows Aristotle's view of the 
origin of springs, lakes, and rivers. Books VI., VII., and 
VIII. treat of the earth's composition, but offer no descrip- 
tion of the different rocks such as one might expect; they 
describe in diffuse style the salts that occur in the earth, and 
the constitution and uses of sand, clay, cultivated soil, etc. 
The consolidation of loose material into rock is ascribed 
to a petrifying force (vis lapidified] inherent in the earth, f 
while a form-giving force (Spiritus architectonicus or plasticus) 
is said to produce all kinds of shapes and figures, for example,; 
crystals, precious stones, stalactites, and fossils. 

Book X. is devoted to mines and minerals. Kircher relates 
that through the medium of Jesuit priests, he put several 
questions to the miners at Neusohl in Hungary. Some of 
these referred to the conditions of temperature in the mines 
whether the heat increased as greater depths were reached 
below the surface, and if there were any signs of subterranean 
fire. The answer from Schemnitz was that in a well-ventilated 
mine the heat was scarcely perceptible, but that with poor 
ventilation the mines were always warm. Johann Schapel- 
mann, an official of the mines in Herrngrund, reported as 
follows: "In dry mines the temperature steadily increases 
in proportion to the depth below the surface ; where water 
lies, the heat is less ; it is greatest in the parts of the mines 
where marcasite occurs." This is the first observation of the 
steady increase of temperature with added depth. 

In spite of its many weaknesses and inaccuracies, Kircher's 
Mundus subterraneus must always command a high place in 
the literature as the first effort to describe the earth from a 
physical standpoint. It was followed in 1672 by the publi- 
cation of the Geographia generalis of Varenius, a work far 
exceeding that of Kircher in critical insight and methodical 
treatment. It is valued as the fundamental work in the 
domain of geophysics. 

Nikolaus Steno 1 was one of the most enlightened geologists of 

1 Nikolaus Steno was born 1638 at Copenhagen, studied medicine and 
anatomy at Copenhagen and Paris, travelled in Holland, France, and 
Germany, and settled in Padua. He was called to Florence to be house- 
physician to the Grand Duke Ferdinand II., and was afterwards the tutor 
of the sons of Cosmo. Steno then accepted an invitation sent by Christian 
V. of Denmark, to return to Copenhagen as Professor of Anatomy ; but 


the seventeenth century. Steno begins his work on the earth's 
crust by comparing fossil teeth found in the deposits of Tus- 
cany with the teeth of living sharks. He then investigates 
the origin of fossiliferous deposits and compares them with 
unfossiliferous rocks. The latter, he says, were formed before 
life existed on the earth, at a time when the earth was 
enveloped in a universal ocean. Homogeneous and fine- 
grained rocks represent, according to Steno, the primitive 
earth-deposits which segregated universally from the undivided 
ocean. If, on the other hand, a rock-stratum be composed of 
particles varying in character and size, or if it comprise large 
fragments derived from other rocks or fossil remains, such a 
layer represents a partial deposit of later origin. 

Steno argued from the traces of salt and the presence of 
marine animals, and even ship flotsam in certain deposits, that 

1 these had been formed on the sea-floor, whereas the presence 
of a terrestrial fauna and of rushes, grasses, and the stems of 
trees in other deposits, indicate that those had accumulated in 
fresh-water basins. Steno was the first to enunciate definite 
natural laws governing the formation of a stratigraphical suc- 
cession in the earth's crust; these may be condensed as 

r follows : (i) a definite layer of deposit can only form upon a 
solid basis; (2) the lower stratum must therefore have con- 
solidated before a fresh deposit is precipitated upon it; (3) 
any one stratum must either cover the whole earth, or be 
limited laterally by other solid deposits ; (4) during the period 
of accumulation of a deposit there is above it only the water 
from which it is precipitated, therefore the lower layers in a 

-series of strata must be older than the upper. 

But Steno also realised that a series of strata originally 
horizontal might become relatively displaced by subsequent 
earth-movements. He cited examples of local crust-inthroiv, 

Steno had become a Roman Catholic, and his stay in his native city was 
embittered by the enmity caused on account of his religion. He returned 
to Florence, and was made Apostolic Vicar of Lower Saxony, dying in 
Schwerin on the 25th November 1687. By command of the Grand 
Duke Cosmo III. his body was brought to Florence and buried in the 
Cathedral of St. Lorenzo. 

Steno's work, De solido infra soliditni naturaliter contento, was first 
published in Florence (1669), anc ^ was intended merely as the prodrome of 
a larger work, but no later work appeared. A second edition was printed 
at Leyden in 1679, but the original text of Steno's little work is now a 
bibliographical rarity; its contents are known chiefly through the i^edium 
of Elie de Beaumont's French translation published in 1832. 


showing how individual strata might remain horizontal, while 
others might be tilted or even be thrown into a quite perpen- 
dicular position, others again might be bent into the form of 
arches. The occurrence of crust-inthrows, together with the 
effects of surface denudation, might give shape to mountains 
and valleys, plateaux, and low- lying plains. Mountains, hej 
said, might also originate from upward action of the volcanic , 
forces in the crust. In cases of active volcanic eruption, ashy ; 
and fragmental rock materials were ejected, intermixed with 
sulphurous vapours and mineral pitch. 

Thus Steno's work already, contained the kernel of much 
that has been under constant discussion during the two cen- 
turies which have passed since his death; and if one reads 
trie most recent text-books of geology, it will be evident that 
science has not yet securely ascertained the share that is to 
be assigned to subsidence, to upheaval, to erosion, and to 
volcanic action in the history of the earth's surface conforma- 
tion in different regions. 

Descartes (1596-1650), in his Principia Philosophies, founded 
a cosmology upon his famous principle of the constancy of the 
amount of motion or "momentum" in the universe. The 
earth, he states, like all other bodies of the universe, is com- 
posed of primitive particles of matter in which a whirling 
motion is inherent, and they have aggregated themselves into 
the form of a sphere. During the gradual cooling of the earth 
the outer layers consolidated as a firm crust, while the nucleus 
still continued incandescent. The coarser and heavier primi- 
tive particles of the earth, as they rotated, collected round the 
centre, while the finer and lighter particles gathered in the 
outer regions and formed the crust, composed of metallic, 
saline, and aqueous parts. Crust-rupture has from time to 
time given origin to continents, seas, mountains, and valleys; . 
according to Descartes, volcanic phenomena and fissure in- 
jections are results of the high temperature of the earth's ! 

G. F. Leibnitz (1646-1716), the mathematician and physicist, 
accepts in his Protogaa the Cartesian view, that primitive 
matter had a fluid consistency owing to the tremendous initial 
heat, and that the earth's spherical form was derived from the 
aggregation of whirling ultimate elements or " monads " of 
matter. In place of the Cartesian principle of momentum, 
Leibnitz starts from a dynamical basis, and assumes a force 


which accomplished the separation of light from darkness, or, 
as he also expressed it, the separation of the more active 
elements of the universe from the more passive. A further dif- 
ferentiation of the inactive elements, according to their stability 
and degree of resistance, determined the dry land and the 
oceans. The escape of heated material from the interior of 
the earth produced slaggy spots on the earth's surface, and as 
these increased a glassy crust was formed. Thus the earth 
was gradually converted from the condition of a radiant sun 
to a dark planet. The cosmical theories of Leibnitz suffered 
in the original from a want of clearness in the diction, and are 
strained on account of the author's conscientious effort to pre- 
sent a historical account of the earth's surface that should be 
in harmony with the Mosaic genesis. 

That part of the Protogcea which deals with mineralogy is 
much more practical. His official position at the Court of 
Hanover enabled Leibnitz to become acquainted with the 
mines and the natural products of the Harz mountains, and he 
gave an account of the mode of occurrence of the metals and 
minerals. He also supplied a detailed description, with illus- 
trations, of a number of fossils occurring in Hanover and 
Brunswick in the copper schists. 

If Leibnitz was careful to make his theory of the earth con- 
form with the Mosaic account of Creation, this feeling was far 
more strongly expressed in England. 

Dr. Thomas Burnet, in his Sacred Theory of the Earth, pub- 

(lished 1 68 1, thinks that in the beginning our earth was a 
chaotic mixture of earth, water, oil, and air, which gradually 
consolidated into a spherical form. The various rock-ingre- 
dients separated out from the primitive chaos according to 
their weight, the heaviest "material accumulating round the 
earth's centre; this in its turn was surrounded by water, on 
whose surface the oily material floated, and the atmosphere 
enveloped the whole. Gradually, the finer particles that had 
been held in suspension in the atmosphere settled upon the 
oil and formed a fatty superficial layer that afforded nourish- 
ment for the first plants, animals, and human beings. 
\ The earth was oval, and its axis stood upright, in the same 
Iplane as the earth's path, hence there were no alternating 
Reasons, no mountains, no seas, no rivers, no storms. It 
'rained only at the poles, but the water filtered at once into the 
earth's interior. This state of earthly paradise lasted 1600 


years, until the moist and fertile superficial layer was dried by 
the heat of the sun, and began to rend and crack. The waters 
below became heated, vapours rose, and bursting through the 
fertile layer, came into contact with the atmosphere. The 
intermingling of air and vapour produced fearful storms of 
thunder and lightning and torrential rains. 

The superficial layer broke in many places, and portions of 
it sank into the earth's abysses. As they fell, some parts were 
crushed, and tumbled in disorder above one another, so that 
they formed mountains, valleys, and islands. This was the 
period of the great Deluge, during which plants and living 
creatures were almost all destroyed. As the floods retreated 
the present state of our earth was initiated, but it also will one 
day pass away in a universal conflagration. Then will succeed 
a second Chaos from which the Golden Age will spring. 

Burnet's circumstantial sketch, which in no way militated 
against Biblical evidences, excited considerable attention, and 
won for him worldly preferment. But in a later work in 1692, 
Burnet treated the Mosaic account of the Fall of Man as an 
allegory, and for this heresy he was dismissed from his appoint- 
ments at Court. 

John Woodward, 1 the collector and palaeontologist, was the I 
most famous English representative of the religious school of 
geologists. His Natural History of the Earth and Terrestrial 
Bodies, etc. (London, 1695), was translated into Latin by 
Johann Scheuchzer, and had a wide circulation. In this 
work, Woodward described his collection of fossils, minerals, 
metals, and rock specimens. He strongly opposed the opinion \ 
that fossils could be mere imitative sports of nature, and said 
they represented past faunas and floras. But he supposed 
these remains to have been carried to their present position in 
the earth by a universal flood, the deluge of the Scriptures. 

Before the Flood, the earth's surface conformation had been 
similar to that which we now know, and the ante-diluvial 
forms of life on the globe had not differed materially from 
post-diluvial forms. The earth's interior had been filled with 

1 John Woodward, born 1665, in Derbyshire, studied medicine under a 
practical physician in Gloucester, was appointed Professor at Gresham 
College in London in 1692, died 1722. He bequeathed his valuable 
collection and library to the University of Cambridge. One of the most 
violent opponents of Woodward's views was Elias Camerarius, Professor at 


I water, which suddenly burst through the earth's crust, and rose 
'. above the highest mountains. The earth's crust was entirely 
disintegrated by this catastrophe, but living creatures, plants, 
and metals remained intact. As the Flood subsided the dis- 
integrated mnterial sank, and the stratigraphical succession 
formed with the heaviest rocks in the lower strata and the 
lighter deposits in the upper horizons. 

Similarly the heavy metals, the minerals, concretions, 
marbles, and heaviest fossils were imbedded in the lowest 
strata; in the chalk strata were buried the lighter conchylia 
and echinoderms ; while the upper series of sandy, clayey, and 
marly strata contained the bones of men, four-footed animals, 
fishes, the shells of terrestrial and fresh-water conchylia and 

The post-diluvial epoch had not been disturbed by any 
further catastrophe ; rain had washed away the superficial 
material from the mountains, and the rivers and streams had 
carried the detritus into alluvial plains and sea-basins. 

William Whiston, 1 another English writer, indulged in still 
more remarkable fancies about the early history of our globe. 
He supposed the earth had originally been a comet, which 
happened to approach the sun, and was melted into a coherent 
mass. As it travelled away from the sun, a re-arrangement of 
the earth's material began ; the heavier particles formed a solid 
nucleus, the lighter particles gathered in the superficial parts; 
the surface was covered by water except where high mountain 
chains and islands rose above the ocean-level. The Paradise 
of the Bible was situated in the southern hemisphere, under 
the Tropic of Capricorn. In the beginning of creation the 
earth had no rotatory movement round its axis. That did not 
begin until after the Sin and Fall of Man in Paradise. After 
the Fall, in virtue of the rotatory movement, the internal heat of 
the earth radiated towards the surface and encouraged a rich 
increase of plant and animal life, but also caused a strong 
development of the human passions. The punishment came : 

1 William Whiston, born 1666, in 1695 became Chaplain to the Bishop 
of Norwich, and was in 1701 recommended by Sir Isaac Newlon as his 
successor to the Chair of Mathematics in Cambridge. The heterodoxy of 
his writings caused Whiston to be deprived of his Professorship in 1701. 
The wide intelligence and imagination of his writing commanded, however, 
a large circle of admirers, and his Theory of the Earth ran through six 
editions in a very short time. He died in 1753. 


on the 1 8th November 2349 B.C., a great comet stood above 
the Equator, its tail came into contact for some hours with the 
earth, shook out waterspouts, and simultaneously the subter- 
ranean waters escaped and inundated the earth's surface. The 
Flood destroyed plants, animals, and human beings. 

The famous zoologist, John Ray, in his Three Physico- \ 
theological Discourses (London, 1693), took much the same \ 
standpoint as Woodward. He accentuated, however, the great * 
importance of running water as an agent of surface erosion, 
and explained the wide continental flats and deserts as a result 
of the occasional escape of subterranean waters and the occur- 
rence of gigantic floods. 

Johann Jacob Scheuchzer, the Zurich professor, turned his 
attention to geological, geographical, zoological, and botanical 
pursuits during his frequent travels, and was an ardent fossil and 
mineral collector. A few geological sections which he made 
in the neighbourhood of Lake Lucerne were the first attempts 
in the literature to reproduce bent strata and other features of 
mountain structure by means of accurate sectional drawing. 
But his works afforded as little insight into the mineralogical 
composition and stratigraphy of the rocks, and the distribution 
of fossils, as those of his predecessors and contemporaries. 

Italy, at the beginning of the eighteenth century, possessed 
two geologists, Antonio Vallisnieri and Lazzaro Moro, who 
sought to counteract the tendency of their time towards the 
theoretical construction of an earth history. Vallisnieri (1661- 
1730), who held the post of Professor of Medicine at Padua, 
was an enthusiastic fossil-collector, and entered strong pro- 
test against the idea that the Flood was accountable for the 
annihilation of all pre-existing organisms. His writings point 
out that marine deposits are widely distributed in Italy at both 
sides of the Apennines, and are also present in Switzerland, 
Germany, England, Holland, and other lands, and Vallisnieri 
therefore argues that those deposits prove incontestably the 
former presence of the sea over these localities. He favours 
Strabo's doctrine, and explains how different areas of the 
earth's surface may have frequently undergone relative changes 
of level, how portions which are now dry land may formerly 
have been under sea-water. He further explains the presence 
of marine fossils in these deposits, on the natural assumption 
that the inhabitants of the sea as they died fell to the bottom, 
and were there incorporated in the deposits. Vallisnieri 


enumerates the known cases of fluctuations of level, and men- 
tions changes going on at Pozzuoli. He gives also a detailed 
account of the island of Mea Kaumen that appeared off Santorin 
in the year 1707. 

The learned abbot T Antonio Lazzaro Moro (1687-1740), 
warmly contested the views of Burnet, Woodward, and Leib- 
, nitz. Moro's own theory of the earth was based upon the 
\ upheaval of the new volcanic island at Santorin. The emer- 
gence of the island was marked by earthquake and volcanic 
disturbances, which went on intermittently for several months. 
Moro attaches great importance to the fact that the rocks, as 
they began to rise from the JEgea.ii Sea, were covered with 
oysters, and that these were afterwards buried by the ejected 
volcanic material. He then describes the origin of Monte 
Nuovo, near Naples ; and, following Paragallos for the most 
part, he gives a complete account of the eruptions of Vesuvius 
from the year 79 AD., and of the eruptions of Etna. His doc- 
trine was that the fossils found in the mountains had originated 
where they were found, and that the mountains themselves had 
been upheaved from the sea by volcanic action. All continents 
and islands had also been upheaved in this way. The stratified 
material composing some mountains represented the original 
volcanic ejections, which in consolidating had assumed a 
certain stratification of a secondary character, such as is 
presented at Monte Nuovo, Vesuvius, and Etna. 

It is unnecessary to enter into the details of the sequence 
of events drawn up by Moro in the part of his work devoted 
to the earth's history. With the exception that he follows 
Vallisnieri in discarding the Flood, the chain of events is 
designed in harmony with Scriptural authority; and an official 
affidavit is given in the preface that the book contains nothing 
which is inimical to the Catholic faith. Moro was highly 
esteemed in his time, and was very successful in spreading 
his teaching. But he contributed little that was new to 
science. Even his doctrine of convulsive upheavals had 
been largely anticipated by Strabo ; while his own con- 
temporary, Robert Hooke, had worked along similar lines, 
although his writings were unknown to Moro. 

A striking contrast to the work of Moro is presented by the 
Telliamed (anagram of the author) of De Maillet. _ Whereas 
Moro attributed all continents, mountains, and islands to 
volcanic agency, De Maillet regards all the rocks of the earth 



as marine deposits. Tci/iamgJwas written in 1715 and 1716, 
but did not appear until 1748. On account of its heterodoxy, 
De Maillet would not allow its publication until after his death. 
The book is written in the form of dialogues between an 
Indian philosopher, Telliamed, and a French missionary. All 
the heterodox ideas of the author are placed in the mouth of 
the oriental, and it is left to the listener to adopt them or to 
reject them. 

The subject-matter is divided into six dialogues. The first 
dialogue starts upon the hypothesis that in the beginning the 
whole earth was covered by water. As the water diminished 
in volume, mountains, islands, and continents made their 
appearance. The highest or primitive mountain-systems 
emerged from the world-ocean at a time when the seas were 
very sparsely inhabited by organisms, hence these rocks are 
either unfossiliferous or poorly fossiliferotis. By the erosion 
and fragmentation of these primitive rocks the material for 
the further formation of rock was obtained. Sediments were 
continually in process of deposition in the seas, and the 
younger the rocks, the more richly they became filled with 
the remains of animals and plants. Telliamed also notes that 
many species of fossil mollusca are apparently now extinct. 

The second dialogue brings forward a number of evidences 
in support of Telliamed's hypothesis that the level of the ocean 
was formerly higher. Telliamed reckons the lowering of the 
sea-level at a foot in three hundred years, or three and a quarter 
feet in a thousand years. The third dialogue suggests various 
methods by which a more accurate determination of the lower- 
ing of the sea-level might be obtained. The fourth is devoted 
to fossils, the origin of which from living organisms Telliamed 
firmly believed in. The fifth and sixth dialogues treat of the 
cosmology of the earth, but are distinctly weaker than the fore- 
going. If we except these concluding chapters, the Telliamed 
far outshines other geological writings of the eighteenth century 
in its wealth of observed facts, its daring originality, and its 
charm of style. 

A few other notable works of the eighteenth century may 
be briefly mentioned. The Englishman Needham, writing 
in 1769, assumed, like Leibnitz, a central fire in the earth, 
and traced to it the origin of mountains and volcanoes. 
He thought the concentric arrarigement of the strata upon 
mountains indicated that these strata, and the fossils contained 



in them, represented marine deposits that had been pushed 
upward by the expansive force working centrifugally through 
the earth. Needham explained the Mosaic "Days" as primi- 
tive periods of protracted length. 

Justi, in his Geschichte des Erdkorpers (Berlin, 1771), 
regarded all planets and comets as torn fragments of the sun. 
The Earth was originally a mixture of soft earth and water, 
mixed with oily and mercurial substances. The spherical 
form was developed as a result of rotation round an axis. The 
water taken from the sun distributed itself over the globe, 
and the latter became enveloped by a vaporous atmosphere. 
Life began to inhabit the water, and minerals and the various 
kinds of rock were formed by new combinations of the original 
ingredients. The whole work is a compilation of fancies hung 
on a few slender pegs of fact. 

Other German writers, Gleichen-Rosswurm, Professor 
Johann Gottlob Kriiger, and Johann Silberschlag, allowed their 
imagination to carry them into still more glaring absurdities. 
But it is worth mentioning that Rosswurm, in sketching the 
development of life on the globe, begins with the existence of 
infusoria in the sea. The skeletons of these are said to have 
formed an " elementary earth " on the sea-basin, from which 
sprang larger and rougher forms of animals, until at last, after 
immeasurably long epochs, all aquatic forms of animal life had 
come into existence. 

Beginnings of Geological Observation. The true spirit of 
research was still kept alive by men who confined themselves 
to special subjects of investigation, or described the strati- 
graphy of particular localities. 

Friedrich Mylius published in 1704 and 1718 a valuable 
work on the rocks of the Thuringian district. John Strachey, 
in England, gave an admirable description of the various kinds 
of strata present in the coal districts of Somerset and North- 
umberland (Philos. Trans., 17 14 and 1725). Holloway studied 
the chalk deposits in Bedfordshire (Philos. Trans., 1723). 

In Italy, Spada and the Sicilian observer, Schiavo, drew 
attention to the fossiliferous deposits of the younger Tertiary 
periods; the Venetian teacher, Donati, compared the present 
deposits and fauna of the Adriatic Sea with the deposits and 
fossils at the base of the Apennines. Baldassari contributed 
a similar work on the deposits near Siena. The traveller 


Targioni Tozetti, of Tuscany, occupied himself with the fossil 
lenticles (Nummutitcs) of Casciano and Parlascio, which he 
took for corals, and also with the fossil remains of land mam- 
malia that are distributed in the valley of the Arno, in Val di 
Chiana, and Ombrosa. Targioni showed conclusively that the 
mammalia had lived in these valleys, and had not been 
carried there by any diluvial catastrophe, or brought by the 

To Christopher Packe we are indebted for the first geo- 
logical map of a part of England in his work, A New 
Philosophical-Chorographical Chart of East Kent^ published in 
1743. The map embraces a district of 32 English miles in 
the east of Kent, and the descriptions in the text are illustrated 
in the map by special signatures and lines. 

Lehmann 1 had an ample knowledge of the minerals 
and fossils that occur in the rocks of Prussia. His work, 
Versuch einer Geschichte des Flotzgebirge (Berlin, 1756), con- 
tains a wealth of carefully observed data, and an elaborate 
statement of his ideas about the origin and composition of the 
earth's crust. Lehmann accepts a universal deluge, which V 
dissolved or carried away in suspension much of the loose 
surface material of the primeval mountains. The fine earth 
and clay thus removed was precipitated as horizontal layers 
on the sides and at the base of the mountains, and formed 
the stratified deposits (Fidtzgcbirgc). As the waters receded, 
these deposits, together with the remains of plants and animals 
that had fallen upon the sea-floor, hardened into solid rock. 

Lehmann distinguished the primitive rocks from those of 
derived origin by their greater height, and by the nature 0f the 
veins or dykes (Ganggesteine) that occur in them. He did not, 
however, differentiate between the mode of origin of the so- 
called vein-rocks and the stratified systems. He thought the 
vein material had also originated from water, but had been 
laid down in disorder in the early periods of creation before 
the universal deluge, so that it was vertically or diagonally 
deposited, and contained few or no fossils. 

1 Johann Gottlob Lehmann was a teacher of mineralogy and mining in 
Berlin. His writings extend over chemical, mineralogical, geological, and 
mining subjects. In 1761 the Czarina Catherine elected him Professor 
of Chemistry, and Director of the Imperial Museum at St. Petersburg, but 
he died in 1767 from injuries caused by the explosion of a retort filled with 


The chief merit of Lehmann is his accurate description of 
the stratified rocks (Flolzgebirge). He distinguished thirty 
successive bands of rock in the stratified system of Ilfeld and 
Mansfeld, and set forth the geological structure of that district 
in an accompanying series of diagrams and sections. Many of 
the terms in his description of the Thuringian deposits were 
adopted by him from the miners, andTKave been retained in 
geological literature; for example, Zechstein or mine-stone, 
corresponding to the Magnesian Limestone and shales or 
Upper Dyassic group in England; and rothes Todtliegendes 
(Rothliegende) or red underlyer, the unproductive basement beds 
below the ore-bearing, and the equivalent of the Lower Dyassic. 

What Lehmann accomplished for the Permian rocks of 
Thuringia was accomplished by one of his contemporaries, Dr. 
Fiichsel, 1 for the Triassic series in the same district. In his 
Latin work, Fiichsel defined for the first time the scientific 
use of the terms Stratum (Schicht), Situs (Lager), and Series 
montana (Formation). He used the term "formation" to 
signify a succession of strata, which have been formed imme- 
diately after one another under similar conditions, and represent 
one epoch in the history of the earth; and this is the signifi- 
cance which has -continued to be attached to the term in 

Fiichsel recognised nine formations in Thuringia from the 
oldest or fundamental rocks to the Muschelkalk : 

9. Muschelkalk, or Upper Limestone series (Middle Trias 
of later authors) ; 

8. The Sandstone series (now Bunter sandstones or Lower 

7, Granular Limestone and dolomitic marls (now Zechstetn 
dolomite) ; 

6. The Metalliferous series (Zechstein) and copper slate 
(Kupfers chief er) ; 

5. White rocks, with interbedded sand and clay; 

4. Red rocks, with interbedded red marble ; 

1 G. Christian Fiichsel (1722-73) studied in Jena and Leipzig, took the 
degree of Doctor at Erfurt, and passed the great portion of his life as a 
physician in Rudolstadt. The results of his investigations are published in 
two works; the chief work appeared at Erfurt in 1762: " Historia terrre 
et maris ex historia Thuringiae permontium descriptionem erecta" (Ada 
Acad. elect. Moguntince). The second work was published independently, 
and is now very scarce, Entwurfznr dltesten Erd ttnd Menschen Geschichte, 


3. Slates, with intercalations of marble ; 

2. Carboniferous series (with this Fiichsel erroneously in- 
cluded the Rothliegende, or Lower Dyas) ; 

i. Basal, or "Vein" series, forming the summits of the 
Harz and Thuringian forest, with erect strata. 

Fiichsel carefully observed and described the fossils charac- 
teristic of the Muschelkalk, Buntsandstein, the Zechstein, and 
other series. 

Fiichsel's great work, though it was unfortunately but little 
known during its author's life-time, became practically the 
model for the Wernerian School of geologists, and, more than 
any other individual work, laid the foundation of that rapid 
development of stratigraphical geology which began in Germany 
in the next generation. He gave to the geological formation a 
definite palseontological value, and also represented the surface 
outcrop of the several formations upon an orographical map by 
means of corresponding signs, letters, or numbers. Fiichsel's 
geological maps were the first of the kind in Germany, and his 
text was further illustrated by detailed geological sections. 

Professor Arduino, 1 in Padua, was the most brilliant of the 
early Italian stratigraphers. He was the first who sub-divided 
the stratified rock- succession into Primitive, Secondary, and 
Tertiary groups. His geological observations were made on 
the rocks of the Paduan, Veronese, and Vicentine districts and 
the neighbouring High Alps, and he gave an excellent exposi- 
tion of the composition, surface outcrop, and order of super- 
position of the strata in the groups which he distinguished. 

According to Arduino, the Primitive rocks are unfossiliferous, 
and consist of glassy, micaceous, strongly - folded schistose 
rocks, through which run innumerable veins of quartz. The 
Monies secundarii contain a great number of marine fossils, 
and are composed chiefly of limestones, marls, and clays. 
Arduino enumerates several minor groups within the Secondary 
series, and dwells at considerable length on the uppermost 
white and reddish limestones, the so-called Scaglia (Cretaceous 

1 Giovanni Arduino (1713-95) was Director of Mines in the Vicentine 
Province and in Tuscany, afterwards Professor of Mineralogy at Padua; he 
exerted a strong personal influence upon his colleagues in Italy and upon 
the many foreign geologists that came to Italy for purposes of study. His 
writings were very numerous and won him great repute. A list of them is 
given in the Bibliographic geologique ct paUontologique de V Italic, Bologna, 


formations). He remarks the huge blocks of granite and 
schist which bestrew the exposed surfaces of the Scaglia rocks, 
saying that they have been clearly carried here from Primitive 
rocks exposed in the neighbouring Tyrol. But it remained for 
a future age to penetrate the mystery of the transport of these 
massive blocks by ice. Arduino's Monies tertiarii consist of a 
younger and highly fossiliferous series of limestone, sand, marl, 
clay, etc., and he observes that the materials of these can 
in many cases be shown to have been derived from the 
Secondary series. 

The volcanic rocks of Northern Italy were comprised by 
Arduino in a separate group, and their different origin was 
clearly pointed out; he included in the volcanic group not 
only true lavas and tuffs, but also the fossiliferous strata with 
which the volcanic rocks were interbedded. Arduino accord- 
ingly referred the origin of the volcanic group to recurrent 
eruptions and intermittent inundations of the sea. 

The first coloured geological map was published by Gottlieb 
Glaser at Leipzig in 1775. Wilhelm von Charpentier published 
three years later the Mineralogy of Chur-Saxony, which ranks 
along with the works of Lehmann and Fiichsel as a classic in the 
early geological literature of Germany. The distribution of the 
principal rocks and formations is shown by means of colours 
on a large map, and the occurrence of the less important 
rocks, of mineral veins and volcanic dykes, is indicated by 
various signs. 

Charpentier grouped granite, gneiss, mica schist, porphyry, 
and limestone together as a basal formation belonging to one 
and the same geological epoch. Above this basal formation 
Charpentier distinguished argillaceous schists and slates, and 
the greywackes of the Carboniferous series ; then the Flotz, or 
ore-bearing group, which he sub-divided according to Lehmann 
and Fiichsel. 

Some years later, by the discovery of Goniatites and fossil 
plants in the slates and greywackes, Von Trebra, an overseer 
of mines, was able to confirm Charpentier's conclusion, that 
the true position of these rocks in the succession was above, 
and not along with the basal formation. 

While the foregoing authors were conducting stratigraphical 
researches in special localities, others were endeavouring to 
enlarge our arena of knowledge by means of travel and by 
observations of a more general character extended over wide 


areas. One of the most notable workers was the versatile 
Guettard, 1 who travelled through France, England, Germany, 
and Poland, and whose great desire it was to reproduce his 
scientific observations on maps. 

Guettard's mineralogical map of France and England r 
naturally cannot compare with the present Geological Survey j 
maps ; but it certainly gives so much accurate information j 
regarding the local occurrence of rocks and minerals, and the ' 
position of mines, quarries, fossil localities, mineral springs, 
hot springs, coal, etc., that it can still be used with advantage. 
The map is not coloured. The accompanying text refers only 
in a very meagre and unsatisfactory manner to the strati- 
graphical succession of the rocks. 

It was a pet scheme of Guettard's to publish a mineralogical } 
atlas of the whole of France. This gigantic plan was never \ 
completed; Guettard, in collaboration with his colleague, the 
chemist Lavoisier, published twenty-nine parts, and Monnet, 
in 1780, added thirty-one farther sheets. Indirectly, this idea 
of Guettard's was productive of very important results, for the 
preparation of the maps demanded an energetic search in the 
open field for the necessary data. The enthusiasm of Guettard 
inspired others, and there rapidly appeared a large number of 
scientific papers on the mineralogical features of different 
French terrains. One very interesting paper gives an enthusi- 
astic account of the neighbourhood of Paris, its rocks, its 
minerals, and a large number of fossils. 

Guettard described the processes of land denudation effected 
by the solvent and destructive agency of rain and rivers, and 
by the abrasion of the waves. This is probably the first paper 
in which a systematic account of denudation is given in its 
relation to changes in the configuration of the earth's surface. 
But the most brilliant of Guettard's achievements was his 
discovery of the volcanic rocks in the Auvergne region. 

In 1757 he was journeying to Moulins and Riom, when he 
observed that black stones were very common on the roads 
and in buildings. Recognising that these were fragments of 
volcanic lava, Guettard, accompanied by his friend Malesherbes, 

1 Jean Etienne Guettard (1715-86), son of an apothecary, while still a 
boy displayed a passion for natural history, especially for botany ; studied 
medicine in Paris, afterwards accompanied the Duke of Orleans on his 
travels, and was made keeper of his natural history collections. In 1734 
he was elected a member of the French Academy. 


followed the traces of the lava, and was thus guided to the ex- 
tinct volcanoes in Auvergne, which had up to that time been 
unknown in mineralogical science. His famous paper, entitled 
"Sur quelques montagnes de la France qui ont ^te Volcans," 
was presented at the Royal Academy of Sciences in 1752, and 
published in 1756. His paper on basalt was published in 

Giraud Soulavie, abbot at Nimes, investigated the extinct 
volcanoes in Vivarais, Velay, Auvergne, and Provence. His 
chief book, Histoire naturelle de /a France mendionale (Nimes, 
1780-84), gave an accurate description of the rocks of the 
neighbourhood. In it Soulavie strongly advocated the vol- 
canic origin of basalt, and described minutely the physical 
peculiarities and the divisional planes of basalt rock. He also 
made an attempt to determine a chronological succession of 
the volcanic eruptions upon the basis (i) of the position of 
the basaltic flows above or below rocks of other composition 
and origin, (2) of the preservation of the scoriaceous and 
slaggy surfaces, (3) of the variations in the height of the 
extinct craters. Even although the succession drawn up by 
Soulavie could not be other than faulty, owing to the ele- 
mentary state of stratigraphical knowledge at that time, it was 
a remarkable piece of work, and fully justifies for him a high 
place amongst the geologists of the end of the eighteenth 
century. His own contemporaries were inclined to see rather 
the weaknesses than the excellences in the work of the country 
abbot. Many of Soulavie's conceptions and observations have, 
however, proved themselves to be eminently fruitful and valu- 

Rouelle, a lecturer on chemistry, seems to have been an 
exceptionally acute thinker. In a short introduction to a 
series of lectures on chemistry, Rouelle touched on the origin 
of the earth and the composition of its crust. He distinguished 
"an old and a new earth." To the first he reckoned granite, 
in the latter he placed all calcareous, argillaceous, and arena- 
ceous rocks, together with the fossils contained in them. The 
fossils were, he said, distributed in the succession of rocks in 
a definite order of development, and these extinct forms had 
differed in the different lands according to environment and 
climate, just as the existing faunas and floras differ in different 
localities at the present day. Rouelle further explained the 
coal seams as accumulations of plants; the rough limestone 


of Paris as a mass of fossil molluscs, amongst which the genus 
Cerithia predominated ; and the limestones in Burgundy and 
in the Morvan as similarly an aggregated mass of ammonites, 
belemnites, and gryphites. Unfortunately, Rouelle published 
nothing more than the bare outline of his ideas, and they failed 
to benefit the general development of geology. 

A Swedish mineralogist of wide repute was Johann Ferber, 
who taught first in St. Petersburg, afterwards in Berlin, and 
finally settled in Switzerland. He was an indefatigable 
traveller, and wrote interesting series of letters relating his 
impressions and observations during journeys in nearly all 
European countries. His description of the neighbourhood 
of Naples, and still more his account of the ejected rocks 
of Vesuvius, are among the finest scientific writings of the 
eighteenth century. 

Ignaz von Born, an Austrian, was a learned mineralogist, and 
a palaeontologist of far keener insight than most of his con- 
temporaries. Like Rouelle, he realised the great part that 
fossils were destined to play in historical geology, observing 
that successive assemblages of fossils gave indication of the 
different geographical and climatic conditions which had 
obtained in the same area during successive ages. In one of 
his treatises, Von Born recognised that the "Kammerbiihel" 
near Franzensbad was an extinct volcano, but this opinion 
was at the time attacked and contradicted by Reuss, the 

G. L. Leclerc de Buffon}- It was only natural that misgivings 
should have been aroused in the minds of many thinkers 
regarding a science whose literature frequently indulged in 
unfounded and fantastic hypotheses, and whose votaries seemed 
often to arrive at worldly distinction without having displayed 
any deep scientific knowledge or accurate observation of 

Buffon gave expression to this widespread feeling among his 
contemporaries when he made the sarcastic remark that 

1 George Louis Leclerc de Buffon, born at Montbard in Burgundy in 
1707, was the son of a wealthy land-proprietor and Member of Parliament, 
Benjamin Leclerc. In the early part of his scientific career, he devoted 
himself to physics and mathematics, but was appointed in 1739 to succeed 
Dufay as Director of the Botanical Garden at Paris. He received the title 
of Count with the surname De Buffon. He died in Paris in 1788. 


geologists must feel like the ancient Roman augurs who could 
not meet each other without laughing. Nevertheless, he 
resolved to gather together all the actual observations hitherto 
recorded in geological science, and to construct a more reason- 
able history of the earth upon this recognised basis. 

His first geological work, Theorie de la Terre, which was 
published in 1749, marked little advance upon current 
literature, but it was an able argument against the principles of 
the earth's origin held by Whiston, Burner, Woodward, and 
Leibnitz, and boldly denounced the popular idea of a universal 
Deluge. His great work, kpoquts de la Nature, appeared 
twenty-nine years later, in 1778. 

Buffon there enumerates five " facts " of first importance, 
and five additional " monuments " or comments. The " facts " 
are physical in character; they postulate the oblate-spheroidal 
form of the earth; compare the small amount of heat received 
from the sun with the large supply possessed by the body of 
the earth; the effect of the earth's internal heat in altering the 
rocks of the crust; and the presence of fossils everywhere over 
the earth, even on the tops of the highest mountains. The 
" monuments " assert that all limestones consist of the remains 
of marine organisms, and that in Asia, America, and the North 
of Europe the remains of large terrestrial animals occur at a 
small depth below the surface, showing that they apparently 
dwelt in these regions at no very remote age; whereas the 
deeper-lying remains of marine creatures in the same region 
belong to extinct species, or are related only to forms now 
inhabiting far distant seas. 

Starting from these axioms, Buffon portrays in very attractive 
terms the beginning, the past, and the future of our planet. 
He derives the material of our earth and the other bodies of 
the solar system from the impact of a great comet with the sun. 
The earth's material assumed the form of a spheroid flattened 
at the Poles, and for 2,936 years continued in a molten state. 
This was the first epoch in Buffon's scheme, and he determined 
its length of duration by a series of experiments with balls of 
melted iron of different sizes. In the same way he determined 
the duration of the molten state to be 644 years in the case of 
the moon, 2,127 for Mercury, 1,130 for Mars, 5,140 for Saturn, 
and 9,433 years for Jupiter. The period required for the earth 
to cool down to its present temperature was calculated by 
Buffon to be at least 74,800 years. 


To the second epoch (circa 35,000 years) Buffon assigns the 
gradual consolidation of the material at the earth's surface. 
The occurrence of rents in this primitive crust allowed the 
influx of molten metallic ores, and was the first cause of surface 
irregularities. At the commencement of the third epoch (ca. 
15-20,000 years), the cooling of the earth proceeded so far that 
the atmospheric vapours were precipitated and gave origin to 
the primitive universal ocean. Then began the development of 
life in the warm waters and the accumulation of marine sedi- 
ments. Gradually the mountains and continents appeared, the 
tapering of the continents towards the south being due to the 
rush of oceanic currents from south to north. The fourth 
period (ca. 5000 years) was signalised by a sudden accession 
of the earth's internal heat, with the result that violent volcanic 
eruptions burst forth, and were accompanied by gigantic 
convulsions of the earth's crust. 

The fifth period saw calm restored, but the equatorial regions 
were still so hot as to be uninhabitable. Life flourished over 
large continental regions at the Poles, and the large terrestrial 
animals, elephants, mastodons, the rhinoceros, and others, came 
into existence. As the heat continued to diminish, the faunas 
and floras gradually migrated southward. 

The sixth period saw the decimation of a continuous 
northern continent into several portions, and many local 
changes in the extent and position of the seas. Man appeared 
and began to struggle with lower creation for the means of 

The seventh period is the epoch of Man's lordship in the 
world, and this will continue until the earth cools to a tempera- 
ture twenty-five times colder than that of the present age, when 
all Creation on the Earth's surface will be annihilated. 

Buffon's merit consists in the bold construction and masterly 
exposition of a theory which for the first time brought the 
historical possibilities of geology to the forefront. His calcu- 
lation of the duration of the successive epochs had, it is true, 
no empirical basis. Yet it made sufficiently clear to all readers 
the author's desire to insist upon long periods of time for the 
slow processes of change in the earth's configuration, and for 
the appearance of successive forms of plant and animal life. 
Some of the noteworthy advances made by Buffon were the 
differentiation which he drew between the primitive rocks 
formed in the second period, and the sedimentary and volcanic 


rocks of the next periods; his clear conception that the oldest 
inhabitants of the ocean had become extinct and been 
succeeded by younger forms; his allocation of the early home 
of the large Mammalia in Polar districts; and his belief, based 
upon the distribution of land faunas, that the Old and New 
Worlds had once been united as a wide Northern Continent. 

The weaker features of Buffon's work are his views about the 
origin of mountains and valleys, which are far behind those 
of Steno, and appear to have been taken for the most part 
from the Telliamed. He also neglected to incorporate the 
important results attained by Lehmann, Fiichsel, Arduino, and 
other stratigraphers. At the same time, Buffon was undeniably 
one of the most gifted exponents of that speculative direction 
which characterised the geological writings of the sixteenth, 
seventeenth, and eighteenth centuries. This period, however, 
contributed a large amount of useful material towards our 
knowledge of the earth, and its many theoretical failures 
brought men at last to a clearer preception that the materials 
for an accurate history of the earth must be looked for in the 
earth itself. But the key had not yet been discovered to the 
solution of a chronological succession of rock-formations ; the 
study of stratigraphy was still in its infancy, and the merest 
beginning had been made in the investigation of deformation 
of the crust and mountain structure. 

Volcanoes and Earthquakes. The phenomena of volcanoes 
and earthquakes have always attracted a large share of 
attention from geologists, not only in virtue of their majesty 
and splendour, but also because of their destructive effects 
upon human life and property. The philosophers of antiquity 
for the most part associated volcanoes and earthquakes with a 
molten earth-nucleus, or with special subterranean centres of 
eruptivity, and the majority of the authors in the sixteenth, 
seventeenth, and eighteenth centuries supported one or other 
of these views. 

Martin Lister had a theory that when sand or other material 
with an admixture of sulphur weathered in the atmosphere, the 
sulphur became heated and exploded, causing volcanic erup- 
tions. Lemery, in 1700, put Lister's theory to experimental 
test; he showed how a mixture of sulphur, iron filings, and 
water imbedded in earth becomes heated, and finally bursts 
ope'n the earthy covering and emits flame and vapour. 


The submarine eruptions at Santorin, in 1707, were fully 
reported by Vallisnieri and Lazzaro Moro, but Mount Vesuvius 
was the volcano which proved the chief source of interest 
throughout the sixteenth, seventeenth, and eighteenth centuries, 
when it was visited by cultured men of all countries during 
their travels in Italy. 

The Royal Librarian in Naples, Father della Torre, in 
1755 compiled a complete record of all the active eruptions 
and other phenomena observed at Vesuvius from 79 the 
middle of the eighteenth century. Valuable information about 
Vesuvius, Etna, and the surroundings of Naples is contained 
in the letters addressed by the English ambassador at Naples, 
Sir William Hamilton, to the President of the Royal Society in 
London. And the handsome volume, with fifty-nine coloured 
plates, by the same author still holds its reputation as one 
of the most trustworthy historical and scientific accounts of 
Mount Vesuvius. 

The progress of travel in the sixteenth, seventeenth, and 
eighteenth centuries gradually added a knowledge of the wide 
distribution of volcanic mountains. Besides the S. European 
volcanoes and Mt. Hecla in Iceland, geographers recognised 
the active volcanoes of Kamtschatka, of Japan, the Sunda 
Isles, the Philippines, the Canary Isles, the Azores, the West 
Indies, Mexico, and Peru. 

Meantime Guettard's discovery of the extinct volcanoes of 
Auvergne gave a new impulse to the mineralogical study of 
the volcanic rocks in that vicinity. 

Nicolas Desmarest, a French Professor, opposed Guettard's 
erroneous conception that the Auvergne basalt pillars had 
crystallised from a watery fluid, and demonstrated the 
resemblance of the Auvergne basalt to certain recent lavas. 
He showed that in the Auvergne district true basalt is 
frequently covered by volcanic ashes or rests upon ashy 
material, that the transition in the field from basalt to 
true lava is quite gradual, and that the basalt everywhere 
presents the character of a volcanic mass that has been 
originally molten and has afterwards consolidated. He 
thought, further, that basaltic rock frequently showed transitions 
to porphyry (trachyte and phonolite), and this again into 
granite, and concluded that all these rocks probably originated 
from a molten state, the granite representing rock solidified ! 
from a less fluid state of the volcanic magma, and basalt 1 


representing rock formed from a completely molten magma. 
In spite of Desmarest's mistaken views about the relationship 
of basalt to porphyry and granite, he was the first clear 
exponent of the igneous origin of these rocks. He was 
besides a pioneer in the comparative method of study- 
ing the igneous rocks. Papers confirming Desmarest in his 
estimate of the igneous origin of basalt, porphyry, and 
granite were contributed by Raspe in Hesse, by Professor 
Arduino in Padua, and by Mr. Strange, the English consul 
in Venice. 

Faujas de Saint-Fond (1742-1819), Professor in the 
Museum of Natural History in Paris, brought forward 
conclusive evidences of the igneous origin of basalt in his 
famous work entitled, On the Extinct Volcanoes of Vivarais 
and Velay. The work contains a detailed mineralogical 
investigation of the ejected material of active volcanoes, and 
compares them with the rocks present in Vivarais and Velay. 
In the course of his journeys in Southern France he found 
a volcanic tuff identical with the Pozzuolo earth, and 
established the flourishing industry of the preparation of 
cement. Saint-Fond's descriptions and illustrations of the 
extinct volcanoes in Vivarais and Velay are excellent, and 
have scarcely been surpassed in later publications. 

The fearful earthquake which destroyed Lisbon in 1755 was 
made the subject of a large number of scientific inquiries 
into the causes of earthquakes. William Stukeley's theory, 
attributing earthquakes to electrical disturbances, gained a 
certain amount of support abroad. Another Englishman, Mr. 
Michell, suggested that the sudden expansion of vapours 
enclosed in fissures and cavities of the earth's crust caused 
earthquakes and volcanoes, the upheaval of mountain-systems, 
and the deformation of the rocks. 

FROM 1790 TO 1820. 

The characteristic features of this age, and that which gave 
it a rejuvenating significance in the development of geology, 
was the determined spirit that prevailed to discountenance 
speculation, and to seek untiringly in the field and in the 
laboratories after new observations, new truths. 


Interest was directed, in the first place, towards the in- 
vestigation and description of the accessible parts of the 
earth's crust. The composition and arrangement of the strata 
were studied with enthusiasm. The bolder inquirers ventured 
into wild recesses of mountain-chains and climbed snowy 
peaks, whose difficulties had hitherto been thought insur- 
mountable ; travellers explored the uninhabited plains of 
Siberia, the remote mountain-ranges of Asia and America, 
and brought home with them new scientific material and 
observations of the highest importance for comparative re- 

The illustrious Professor of Mineralogy at Freiberg, Abraham 
Gottlob Werner, exercised an unrivalled authority amongst the 
followers of the strict descriptive method in natural history. 
By the skill and eloquence of his teaching, far more than by 
his books and writings, Werner inspired in his scholars and 
adherents a devotion towards exact methods of study. The 
public lectures given by Werner systematised for the first 
time the subject-matter that should properly come within the 
domain of that rapidly growing branch of science for which he 
originally suggested the name "Science of Mountains," but 
afterwards called "Geognosy." Werner included in his system 
of geognosy the mineralogical identification of the rocks, also 
the minerals present in them, and their special places of occur- 
rence, the determination of the stratigraphical position of the 
rocks, their thickness, and mutual relationships, as well as the 
conditions under which they took origin. 

Under the term " geology," suggested by De Luc, Werner 
would only recognise theoretical speculations about the origin 
and history of the earth. Great though the advantages of 
Werner's method were, it was not without its weaknesses. 
The chronological succession of the individual members of a 
formation was not determined with sufficient precision, the 
fossils were scarcely used in determining the age of a rock 
stratum, and the history of organic creation was not even 
recognised as a subject of investigation in geognosy. 

In this respect the great pioneer was the English engineer, 
William Smith. He was the first to make known on incon- 
testable evidence that the stratified rocks of England could be\ 
most securely identified and arranged in chronological order 
according to their organic contents. Smith's method of deter- 
mining the age of rock-strata from the organic remains found 


in them provided an inestimable complement to Werner's 
system, since the latter rested in the main upon mineralogical 
distinctions. William Smith has received the merited appella- 
tion of " father of historical geology." Two French scientists, 
Alexandre Brongniart and Cuvier, attained similar results, 
independently of William Smith, from their examination of 
the fossils in the rocks of the Paris basin. 

Thus the knowledge and comparative investigation of fossil 
faunas and floras came to be recognised as a leading feature 
in the study of rock-formations. Rapid studies were made in 
the new direction of research by Cuvier, Brongniart, Lamarck, 
Schlotheim, Sowerby, and others. The name of Palaeontology 
was given to the special department of zoological and geo- 
logical science that treated of extinct organic forms. 

During this period (1780-1820), while advances were being 
made in empirical methods of study, the theoretical aspect 
of geology remained for the most part on the old lines. 

The theories of the universe presented by De Luc and De 
la Metherie are largely imaginative. Cuvier's Catastrophal 
Theory still betrays the dominating influences of the older 
literature. Werner's hypotheses about the origin and de- 
velopment of the earth scarcely rise above the ideas current 
in the seventeenth and eighteenth centuries. Indeed, the 
erroneous views held by Werner with regard to the origin of 
basalt and of volcanoes, together with the one-sided character 
of his Neptunistic doctrines, appreciably retarded the progress 
of geology. 

The opponents of the Neptunistic doctrines were the 
Plutonists and Volcanists, who numbered in their ranks 
many observers of world-wide repute e.g., Hutton, Dolomieu, 
Von Humboldt, Von Buch, Breislak. Yet the early Plutonists 
had no great array of facts before them, and their teaching was 
necessarily inadequate for purposes of generalisation. 

On the whole, however, the close of the eighteenth and 
beginning of the nineteenth century was a period made 
memorable in geology by the pioneer labours of a brilliant 
phalanx of scientific men Werner, Saussure, Humboldt, 
Hutton, W. Smith, Cuvier, Brongniart, and others. Their 
works and teaching stirred new activity and interest in this 
branch of research in the mining-schools of Europe, and 
numerous adherents gathered round the intellectual heroes 
of the age. Students were attracted by the freshness of the 


mineralogical and geognostic discipline, as it now came to be 
enunciated in professorial courses of lectures, and above all 
by enthusiasm for a science which had largely to be pursued 
out-of-doors, and therefore offered wide scope for the physical 
as well as the mental energies of youth. 

Following the guidance of their great leaders, a numerous 
band of workers, by their unabated zeal in collecting and 
identifying fossils and rock-specimens, no less than by un- 
remitted observations in the field, established the young 
science of geology upon a platform of equality with other 
spheres of scientific knowledge. 1 

Pallas and De Saussure. Pallas and De Saussure are two 
of the few scientific men of the latter half of the eighteenth 
century who endeavoured to explain the surface conformation 
of the earth upon principles of stratigraphy and structure. 
Peter Simon Pallas, born in Berlin in 1741, came of a highly 

1 The chief seats of mineralogical and geognostic teaching at this time 
were the mining-schools; that of Freiberg was founded in 1765, Schemnitz, 
1770, St. Petersburg, 1783, and Paris, 1790. Geology was also associated, 
at least in Germany, with the literature of mining and mineralogy. Voigt 
published a magazine on mineralogy and mining interests (Weimar, 1789- 
91). A number of important papers on geology, mineralogy, and mining 
are contained in C. E. von Moll's Jahrbiicher der Bergund Hullenkunde 
(Salzburg, 1797-1801), a series which continued to be published until 1862. 
K. C. Leonhard's Pocket-book ( Taschenbuch] for Mineralogy was founded 
in 1807, and soon took the first rank among the German journals, which 
it has continued to retain to the present day, its title having been changed 
in 1830 to Jahrbiich fur Mineralogie, Geologic, tind Petrefaktenkunde 
(Palaeontology). Ballenstedt's Archiv fiir d'e neuesten Entdeckungen 
in der Urwelt (Quedlinburg and Leipzig, 1809-24, 6 vols.) were 
chiefly devoted to the occurrence of human remains, diluvial animals, and 
other fossils, likewise to questions of a theoretical nature. In France, the 
Journal des Mines (Paris, 1795-1815) corresponds to these German publica- 
tions. From the year 1816, this magazine received the title Annales des 
Mines, which it still bears. The Journal de Physique, published by Rczier 
and De la Metherie, contains a number of theoretical papers by De Luc 
and De la Metherie, and also important petrographical communications by 
Dolomieu, Cordier, and others. In England, the Geological Society of 
London was founded in 1807, and geological and palneontological papers 
were afterwards published in the Transactions, later in the Proceedings 
and Quarterly Journal of this Society; previously contributions in these 
branches of science had been published chiefly in the Transactions of 
the Royal Societies of London and Edinburgh. In the other European 
States, scientific Societies and Academies were zealous in the publication 
of special papers on geological and palaeontological subjects. 



gifted family. His father was professor of surgery, his mother 
belonged to the French colony in Berlin. His inborn talent 
for languages developed early ; while still at school, he 
mastered French, English, and Latin in addition to his native 
tongue. He studied medicine and natural science at Berlin, 
Halle, Gottingen, and Leyden, and after a visit to England, 
settled at the Hague in 1763, to devote himself exclusively to 
science. The turning-point in his career was an invitation to 
fill the chair of Natural History in the Imperial Academy of 
St. Petersburg, and the further request that he should 
undertake the leadership of an expedition to Siberia, planned 
by Empress Catherine II. 

Pallas spent six years of great privation (1768-74) in 
Eastern Russia and Siberia, exploring the plains, rivers, and 
lakes, with a view both to their geography and to their faunas 
and floras, and he also examined geographically the Ural and 
Altai mountains. 

Partly during the expedition and partly afterwards, Pallas 
published a three-volume work containing an account of his 
travels and observations. Few explorers have contributed 
such a vast wealth of geographical, geological, botanical, 
zoological, and ethnographical observations as Pallas has done 
in this justly famous work. 

In 1793 Pallas commenced a journey of two years' duration 
in Southern Russia and the Crimea. He liked the province 
of Taurida so well that he afterwards took up residence there 
upon an estate presented to him by Empress Catherine. He 
continued his scientific researches for several years, until, 
failing in health and saddened by the loss of his wife, he 
returned to his native city in 1810, and died in Berlin 
in 1811. 

Pallas occupied a high position in the scientific world. 
He achieved his successes mainly in zoological and geograph- 
ical research, but he also contributed much to the progress of 
geology. His geological views are contained in a treatise 
published by the St. Petersburg Academy, Consideration of 
the Structure of Mountain- Chains (1777), and in the Physical 
and Topographical Sketches of Taurida (1794), 

John Michell had in 1760 published in the Philosophical 
Transactions a series of observations on earthquakes and 
mountain-structure. This paper was accompanied by an ideal 
section through a mountain-system, showing a central core 


composed of the crystalline massive rocks, on either side a \ 
succession of uptilted and upheaved strata covered in their 
turn by younger, slightly tilted, or horizontal deposits 1 
composing the neighbouring plains. Michell, however, did 
not draw any general conclusions. Pallas was enabled from 
his wide experience to fill in the details of Michell's skeleton 
plan of a mountain-system. 

According to Pallas, granite forms the core of all great 
mountain-systems. It is covered by unfossiliferous schistose 
rocks of various kinds, serpentine, porphyry, etc. These rest 
against the granite in highly-tilted or vertical positions, and 
are themselves succeeded by argillaceous schists and shales, 
and by thick masses of limestone containing marine fossils. 
The shales and limestones have highly-tilted positions where 
they occur in the inner parts of a mountain-system, but 
become less tilted and horizontal in the outer portions, the 
number and variety of the fossils at the same time increasing. 
The low hills and plains are composed either of sandstone, marls, 
and red clay with stems of trees and twigs of land plants, or 
of loose material, with the bones of large land mammals. 
Pallas examined the mammalian remains with great care. 
He proved the astonishing frequency in the occurrence of 
mammoth, rhinoceros, and bison in the Siberian plains, and 
described a rhinoceros corpse with hide and hair complete, 
imbedded in the sand and pebbles on the bank of the Willui 
river. He also stated that great accumulations of sand 
and sulphur occur in the schistose zone of rocks, and that 
the decomposition of those materials gives origin to volcanic 
disturbances, which however affect only the rocks above the 
schistose zone and the granite. 

The primeval ocean of the globe, in his opinion, never stood 
more than 100 fathoms above the present sea-level, so that 
the granite core of the mountain-chains could not have been 
covered by it. All mountain-ranges composed of schists, lime- 
stone, and younger formations, or, as Pallas called them, the\ 
mountains of the second and third order, owed their upheaval | 
to volcanic force. The schist mountains had originated before 
the creation of living creatures ; then the limestone ranges 
rose above the primeval ocean, and some of these, such as the 
Alps, in relatively recent periods. The mountains of the third 
order were due to the last volcanic eruptions. The upheaval 
of mountain-chains was always accompanied by violent ground- 


tremors and by other disturbances of the earth's surface. 
Great cavities formed in the earth's crust and filled with 
sea-water ; or, sometimes, portions of the continents were 
devastated by floods. In illustration of this, Pallas said that 
at the outbreak of volcanic action in the Indian Ocean and 
South Seas, "which two seas seem to occupy a position above 
one common volcanic arc" the waters of the Equator were 
forced towards the Poles, and carried northward from India 
the plants and animals that now lie buried in the loose gravels 
of the Siberian plains. This was the explanation he gave 
of the occurrence in such remarkable number of bones of 
mammoths, rhinoceroses, and buffaloes in Siberia. 

Although this explanation and many of his opinions 
about volcanoes were erroneous, there can be no 
doubt that Pallas was an accurate observer, and that his 
broadly conceived delineation of the surface conformation, 
general sculpture, and physical characters of a huge and 
hitherto untravelled territory, conferred an inestimable boon 
on the struggling natural sciences. The works of Pallas have 
been the basis of all later geological investigations in eastern 
and southern Russia, in the Ural and Altai mountains, and in 

A life-long student of the French-Swiss Alps, Horace 
Benedicte de Saussure must always be given the place of 
honour amongst the early founders of the science of the 
mountains. Born in Geneva in 1740, the scion of a noble 
and rich patrician family which had already won high 
scientific repute in the previous century, De Saussure en- 
joyed in his early years and education every advantage of 
wealth, culture, and influence. As a boy he rambled in 
the country around Geneva, diligently collecting plants and 
minerals. But the mountains near Geneva failed to 
satisfy the enterprise of the youthful student. At the age 
of twenty he made his first walking tour to Chamonix, and 
from that time resolved to devote his life to the study of the 
Western Alps. Two years later he was appointed Professor of 
Philosophy at the Academy of Geneva. 

In 1787, at the head of a well-equipped party, he carried out 
the first ascent of Mont Blanc. In the following year he 
spent eighteen days in the Col du Geant, at a height of over 
10,000 feet; and between 1789 and 1792, he climbed the 
summits of Monte Rosa, the Breithorn and Rothhorn. In 


1794 a stroke of paralysis put an end to his mountaineering 
activity, and in 1799 he died. 

Saussure's glowing descriptions of the Alpine world removed 
the prejudice against the " Montagnes Maudits," and awakened 
a feeling of enthusiasm for the infinite wonderland of beauty 
and delight in the higher altitudes of the Alps. Apart from 
his achievements in science, De Saussure may be regarded as 
the pioneer of a practically new cult in human enjoyment, the 
love of mountain-climbing. 

His great work, Voyage dans ks Alpes, is a model of clear 
language, exact observation, absence of bias, and cautious 
reserve in forming general conclusions. His style is simple, 
concise, without rhetorical efforts, yet by no means devoid of 
elegance. At the outset De Saussure laid down the principle 
that we need not expect to advance our knowledge of the 
earth's past by a study of flat plains ; that only by solving the 
problems presented to our view in mountain-systems can we 
hope to gain insight into the series of biological and geological 
events in the history of our world. His chief concern was to 
observe accurately ; he placed little importance on theoretical 

The descriptions of his journeys start with the environment 
of Geneva, with Mont Saleve, the Rhone Valley, and the 
south-west Jura, continue into the Dauphine, across the 
Tarentaise and Maurienne group, the Mont Cenis Massive, 
the Ligurian Alps, and embrace the Provence and the Rhone 
Valley. The district examined in greatest scientific detail was 
that of Mont Blanc and the Valais group ; but he also travelled 
through the St. Bernard group, the Berne and Gotthard Alps, 
and the neighbourhood of Lake Lucerne. Everywhere he 
observed and noted the local varieties of rock and the 
occurrences of minerals and fossils. He also entered the 
strike and dip of the strata upon topographical maps, although 
he made no attempt at geological maps and sections. 

In his views on mountains tructure, De Saussure followed 
Pallas. He showed that in the Western Alps, as in the Ural 
mountains, a central core of granite, gneiss, and other primitive 
rocks, was succeeded by stratified but unfossiliferous shales 
and schists of different kinds. The schistose rocks were most 
steeply tilted in the Central Alps, where they came into 
proximity with the primitive rocks, while towards the outer 
Alps the secondary rocks (limestone, sandstone, conglomerates) 


followed in less tilted positions. More striking than this scheme 
of Alpine structure is De Saussure's admirable description of 
the fan-shaped arrangement of the schists in the Central Alps 
of western Switzerland, and his proof that the longitudinal 
valleys and the chains of secondary rock follow the strike of 
the strata and the continuation of the main ridge, remaining 
parallel with the leading or central chain. Saussure further set 
forth the asymmetry of form presented by the Western Alps, in 
respect of their gradual descent to the Swiss plains on the north 
side of the Alps, and their abrupt descent on the Italian side, 
He examined the mineral composition of the rocks, and the 
alternation, succession, and position of the different kinds of 
rock. He also studied the topographical, meteorological, and 
physical relations in the mountains. A permanent addition to 
the facts of physical geography was made by his height measure- 
ments, his observations of electrical atmospheric disturbances, 
his determinations of' the snow-line, rise of temperature in 
the ground and in the depths of the lakes, his investiga- 
tions of glaciers, and of the distribution of plants at different 

It was not until after the publication of the first two volumes 
of his work that De Saussure became acquainted with Werner's 
geognostic and mineralogical writings. He welcomed the new 
methods and additional knowledge supplied by Werner, and 
promptly tried to apply them in the district he was himself 
examining. Hence we cannot blame De Saussure when we 
find in the third and fourth volumes of his work, certain 
ideas about rock structure and mountain upheaval that appear 
contradictory to views expressed in the earlier volumes. 

De Saussure also changed his opinions more than once 
about valley-erosion and about the origin of the immense 
thicknesses of debris and pebble deposits in the Rhone Valley 
and at the foot of the Alps. Like Professor Arduino of 
Padua, De Saussure was intensely interested in the nagelflue 
conglomerates and morainic accumulations and erratic blocks 
on the outer Alpine slopes, but was no more successful than 
Arduino in arriving at an explanation. He referred them all 
to one geological period, during which he thought gigantic 
inthrows of the crust had taken place, and the waters of the 
ocean rushing into the crust-basins had fragmented, torn away, 
and scattered large masses of rock. 

With our present intimate knowledge of glaciation, it seems 


strange that De Saussure should have provided us with a 
minute description of the rounded, hummocky terrains in the 
Alps, which he termed " roches moutonnees," and should even 
have observed the scratches upon these rocks, and yet have 
failed to associate such phenomena at lower Alpine levels with 
anything that he had observed in the higher altitudes. On 
the other hand, realising as we do to day the extreme com- 
plexity of Alpine stratigraphy, it is readily comprehensible why 
in spite of the extraordinary number of his observations, De 
Saussure could not construct from them any definite chrono- 
logical succession of the rock-strata in the Alps. He certainly 
differentiated the secondary Alpine rocks from the primitive 
crystalline masses in the central chain, and distinguished the 
deposits in the plain of Piedmont as Tertiary. 

In his conceptions of the origin of granite, schists, and 
igneous dykes De Saussure followed Neptunistic doctrines. 
Finally, after much hesitation, he allowed that the sedimentary 
series had been deposited horizontally and only subsequently 
elevated and tilted, but he would not agree to the Volcanistic 
teaching that volcanic force had upheaved the rocks. Looking 
back on De Saussure's geological writings, it might seem that 
from their lack of broad generalisations they had failed to 
exert a direct influence upon the progress of Alpine geology. 
Yet their faithful observations have made them reliable books 
of reference for all Swiss geologists to the present day. De 
Saussure's love of truth and his passion for nature, combined 
with the extreme modesty of his attitude towards the science 
of the mountains, have made him an ideal personality in the 
annals of Alpine geology. 

Endless in his energy, insatiable in his desire to accom- 
plish, De Saussure, at the conclusion of his life's labours, writes 
that he has found nothing constant in the Alps except their 
infinite variety. With a feeling of sadness he admits the 
futility of all his efforts to wrest the eternal truths of nature 
from the majestic peaks of his native land. Then it was that 
he wrote his charming book of Instructions to Young Geologists. 
He impresses upon them above all to keep their minds free 
from bias in favour of one scientific opinion or another, to 
make it their chief aim to observe with the greatest deliberation 
and detail, to omit nothing as unimportant, and at the same 
time not to lose sight of the possible value of all facts in 
establishing the fundamental principles of the science. 


A. G. Werner and his School, Leopold von Buch, Alexander 
von Humboldt. Abraham Gottlob Werner, 1 Professor in the 
School of Mines at Freiberg, was the most renowned geologist 
and mineralogist of his day. A born teacher, Werner com- 
bined quickness of observation and a marvellous memory with 
the capacity to marshal all the facts that came under his notice 
into natural systematic order, and to reproduce them orally in 
lucid language at once striking and convincing to his hearers. 
His first original work, On the External Characters of Fossils, 
placed him at once in the front rank of living mineralogists. 
His fame rose still higher when he began in 1780 to deliver a 
course of lectures on the science of rock-formations, or, as he 
called it, " Geognosy." He derived the fundamental concep- 
tions in his teaching of the formations from the admirable 
systematic arrangement introduced by the Swedish mineral- 
ogist, Tobern Bergman. Werner's creation of the study of 
rock-formations into an independent academical discipline was 
far-reaching in its effects. Thoughts that had been vaguely 
shaping themselves in the minds of a few scientific thinkers, 
important contributions to knowledge which had been locked 
up, except for the very learned, in the Transactions of scientific 
societies, were assimilated and mastered by Werner, and 
taught by him with such precision and enlightenment that 
Freiberg became in a few years the European lodestar for the 
study of mineralogy and geognosy. 

The Professor never relaxed his reading and research; his 
lectures were not written, and they were fresh every year. Kept 
in touch as he was with all the great academies and universities 
by the floating body of students whom his teaching attracted, 

1 Abraham Gottlob Werner was born on the 25lh September 1749 
(according to Frisch, 1750). at Wehrau in Saxony. He belonged to a 
family which had been actively engaged in the mining industry for three 
hundred years. His father, who was overseer of a foundry for hammered 
iron work, taught him in his boyhood to recognise nearly all the known 
minerals, and after a short period of residence at a school in Silesia, Werner 
returned to take part in the same foundry as his father. At the age of 
eighteen he visited Freiberg in the course of a holiday tour, and the sight 
of the collections and mining schools there roused in him an enthusiastic 
desire to take up the study of minerals and mining as a career. He studied 
at Freiberg and Leipzig, and in 1774 published his first paper on " The 
External Characteristic Features of Fossils." In 1775 Werner was ap- 
pointed Inspector of Collections and teacher in the School of Mines at 
Freiberg. This post he held for more than forty years, and died unmarried 
in 1817. 


Werner knew the best of the new work that was being done 
elsewhere. From all parts of Europe students came, and, 
when they returned to their own countries, they spread the 
teaching of geognosy and mineralogy as Werner had taught it 
to them. It was the spoken word of Werner that carried. Of 
written words no man of genius could have been more chary. 
His dislike of writing increased as he grew older, till he 
could scarcely bring himself to reply to the most important 
letters. Cuvier relates that the letter which announced to 
Werner that he had been elected a Foreign Member of the 
French Academy was left unopened by the Professor and was 
never answered. 

With the exception of a number of mineralogical papers, and 
a short classification and description of the different rock- 
formations, Werner published only a single work on the origin 
of dykes, and a series of very short articles on basalt, trap- 
rock, and the origin of volcanoes. He never published his 
academical courses of lectures ; for an account of these we 
have to turn to notes published by his students, sometimes in 
abridged and sometimes in extended form. Werner had, how- 
ever, more than once to disown these published notes, as they 
failed to represent the true sense of his lectures. 

The most trustworthy reports of Werner's " geognosy " are 
probably those written by Franz Ambros Reuss in the third 
part of his text-book (Leipzig, 1801-3); by D'Aubisson de 
Voisins in his Traite de Geognosie (Strasburg and Paris, 1819); 
and by Jameson in the Elements of Geognosy (Edinburgh, 1808). 
Werner himself published only one lecture "Introductory to 
Geognosy " delivered at Dresden. 

Werner denned "Geognosy" as the "Science which inquires 
into the constitution of the terrestrial body, the disposition of 
fossils (i.e. minerals, cf. p. 15) in the different rock layers, and 
the correlation of the minerals one to another." In his 
lectures, he began with a short epitome of mathematical and 
physical geography, and with a discussion of the natural 
agencies which alter the conformation of the globe. 

Proceeding to the consideration of the earth's crust, Werner 
described all the varieties of rock and entered in detail into 
their structure, their position, their chronological succession, 
and their technical value as rich or poor metalliferous layers. 
Certain varieties of rock (shale, limestone, trap-rock, porphyry, 
coal, talc, and gypsum) were thought by Werner to have been 


recurrent groups in the rock-succession, and he treated them 
as "suites" or series, characteristic of each successive epoch 
in the earth's history. Largely following the precedent of 
Bergman, who had distinguished four principal rock-formations, 
Werner erected five so-called formation-suites in his chrono- 
logical scheme of the rocks : 

5. Volcanic rocks, sub-divided into true volcanic (lava, 
volcanic scoriae and ashes, pepperino, tuff) and pseudo- 
volcanic rocks (burnt clay, jasper, polishing-stone, slag). 
4. 7'he transported or derivative rocks with the formations 
nagelflue, sand, clay, pebbles, calcareous tufa, bitu- 
minous wood, soapstone, aluminous earth, etc. 
3. The Fiotz rocks with the formations old sandstone, coal, 
old Flotz limestone, the ore-bearing or "Zechstein" 
rocks, bituminous lignite, Muschelkalk, freestone and 
chalk, basalt, pitch-coal, brown-coal, etc. 
2. The transitional rocks with the formations clay-slate, 
crystalline schist, greywacke, transitional greenstone, 
gypsum and the first organic remains. 

i. The primitive rocks with the formations granite, gneiss, 
mica schist, slate, primitive greenstone and limestone, 
quartzite, hornblende schist, porphyry, serpentine, 
chlorite and talc schist, primitive gypsum, etc. No 
organic fossil remains. 

According to Werner, the primitive rocks originated during 
the first chaotic period of the earth before the existence of 
organic creatures, by chemical crystallisation of rock-material 
from an aqueous solution. In the transitional period, the slates 
and shales were held to represent chemical precipitates ; the 
greywackes to have been mechanical deposits. During the 
accumulation of the Flotz series, periods of disturbance 
alternated with periods of quiet deposition ; the waters 
frequently receded from land areas, and again inundated the 
young continents. These varying conditions continued during 
the succeeding epoch of active transportation, and finally gave 
place to an epoch of violent volcanic outbreaks, the immediate 
cause of which Werner believed to be the ignition of deposits 
of coal in the earth's crust. 

Werner's practical knowledge of mining methods served him 
in good stead when he came to study the strike and dip and 
relative position of the rocks from a scientific point of view. 
His application of more exact methods in taking field observa- 


tions, and his introduction of a number of new and precise 
terms for stratigraphical purposes, marked an advance in the 
study of the earth's crust scarcely less important than his 
masterly classification of the rocks according to their mineral 

Unfortunately, Werner's field observations were limited to a 
small district, the Erz mountains and the neighbouring parts 
of Saxony and Bohemia. And his chronological scheme of 
formations was founded upon the mode of occuirence of the 
rocks within these narrow confines. To him in that rich/ 
mining district the minerals seemed all-important, and the 
occurrence of organic remains fell into insignificance. Again,! 
he held strong convictions that the ores preset in vfi nc C11 ^ ri ' 
liiyeTsliaci separated out from supersaturated aqueous solution^ 
of the metals, and he sought to explain in a similar way the 
origin of the massive granitic and schistose kinds of rock. 
The Wernerian doctrine was all the more attractive as it 
seemed so simple. It taught that all the rocks of the crust, 
like the earth's body" itself, had taken origin from aqueous , 
solutions, either as chemical or as mechanical precipitates, 
while volcanic lavas and scoriae represented rock-material that' 
had been so precipitated but had subsequently been melted 
and ejected. 

Werner was equally narrow in his ideas about the strati- 
graphical relationships of the rocks. As a fundamental 
principle he held that all varieties of rock had been deposited 
in the same horizontal or tilted positions as they now occupy. 
But strata inclined at an angle of more than 30 owed their 
high inclination to local disturbances, such as the collapse of 
crust-cavities, landslips, etc. These local inthrows and slips 
exerted little influence upon the connection of the strata as a 
whole ; rather, the successive deposits enveloped the earth 
with the uniformity of the integuments of an onion. 

Werner gave little credence to the opinions of Pallas and 
Saussure regarding the elevation of wide continental territories 
and the upheaval of mountain-chains. Like De Maillet and, 
Buffon, he ascribed the inequalities of surface conformationj 
exclusively to the erosive agency of water, more especially to 
the strong currents created during the retreat of sea-water after 
its periodic inundations of the land. 

Similarly, with regard to the origin of basalt, he came into 
conflict with the results obtained by the leading authorities on 


1 volcanic rocks in his time Desmarest, Raspe, Arduino, and 
" Faujas de Saint-Fond. Werner had at first included basalt 
among the rocks of highest antiquity ; subsequently he re- 
moved it to the Flotz formation. In 1788, after a visit to 
the Scheibenberg, a basaltic summit in the Erz mountains, he 
wrote a special paper on basalt, from which the following 
passage is extracted : 

" The basalt rock is separated by several beds of sandstone, 
clay, and greywacke from the basal gneiss. The transition 
from one stratified bed to the next in upward succession is 
quite gradual. Even the greywacke merges gradually into the 
clays below it and the basalt above. Therefore the basaltic, 
clayey, and sandy rocks all belong to one formation, have 
all taken origin as moist deposits, precipitated during one 
particular epoch of submergence in this district. 

"All basalt was formed as an aqueous deposit in a com- 
paratively recent formation. All basalt originally belonged to 
one widely extended and very thick layer, which has since 
been for the most part disturbed, only fragments of the original 
layer being left." 

Voigt, who had been a scholar of Werner, opposed this so- 
called "new discovery," and said that the Scheibenberg basalt 
was of volcanic and not aqueous origin, that it represented 
an old lava which had flowed over a sandy substratum. A 
lengthy controversy ensued, in the course of which Werner 
wrote his paper tracing volcanic activity to the burning of 
coal in the earth's crust. He argued that during volcanic 
action basaltic deposits might be converted into lava, if it so 
happened that the coal-beds were subjacent to the basaltic 
beds in the crust. The controversy between Neptunists and 
Volcanists waged for many years in Germany, and much labour 
and time were lost in the discussion of difficulties which had 
already been solved in other European countries. 

The New Theory of the Origin of Mineral Veins was 
Werner's last contribution to science. His theory was that 
surface-water descends through crust-fissures ; vein-stuff is 
precipitated from the water, and gradually fills up the fissures. 
Although this theory is no longer accepted for the majority 
of ore-deposits, Werner's work proved of the highest value 
in mineralogical science, since it contained a large store of 
accurate information about mineral veins, and suggested new 
methods of determining the relative age of vein-deposits. 


So strong was the personal influence of Werner, that the 
Neptunian doctrines which he inculcated continued to hold 
their place for several decades until, in fact, three of the 
greatest of his scholars, D'Aubisson de Voisins, Leopold 
von Buch, and Alexander von Humboldt, stepped into the 
ranks of the opponents of Neptunism. 

Leopold von Buch was the most illustrious of the geologists 
taught by Werner. The later writings of Leopold von Buch, 
published between 1820 and 1860, are those on which his 
fame chiefly rests; but from the year 1796 he was actively 
engaged in travel and research, and his earlier writings con- 
tributed in a great degree to establish the science of geology. 

Leopold von Buch was born on the 26th April 1774, at the 
Castle of Stolpe in Pomerania, the son of a nobleman with 
considerable property. While still a boy he displayed a passion- 
ate love of scientific inquiry, and his fondness for chemical 
and physical mineralogical studies led him to select the Mining 
Academy of Freiberg for his collegiate course. While there, 
Alexander von Humboldt and Freiesleben were among his fellow- 
students, and with them he formed close ties of friendship. 
He made his home for nearly three years (1790-93) with 
Professor Werner, for whom he entertained the deepest senti- 
ments of reverence and friendship ; and these were in no 
way altered when, in after years, some of his opinions began 
to diverge from the teaching of Werner. 

Von Buch made several excursions during his student days 
into the Erz mountains and Bohemia, and published a paper 
on the neighbourhood of Karlsbad. From 1793 to 1796 he 
studied in Halle and Gottingen, and became acquainted with 
Harz, Thuringia, and the Fichtel mountains. In 1796 he 
accepted office in the Mining Department of Silesia, but 
resigned in 1797, in order to devote his entire time and energy 
to travel and research. His stay in Silesia resulted in the 
publication of an important treatise on the mineralogy of the 
neighbourhood of Landeck, and an attempt at a geognostic 
description of Silesia. He spent the winter of 1797 in Salzburg, 
together with his friend Alexander von Humboldt, and in the 
following spring set out on his first journey through the Alps 
to Italy. He visited the Euganean Isles and the district of 
Vicenza, and stayed for some time at Rome, making frequent 
excursions into the Albanian mountains. He then spent 
five months at Naples, and devoted a largjtoart of his time 


to Vesuvius. Although during these travels he began to 
entertain serious doubts about the correctness of Werner's 
theory of the origin of basalt, he could not convince himself 
that it was untenable. 

After a visit to Paris, Von Buch returned to Berlin in 1799, 
and was there commissioned to investigate the occurrence of 
mineral contents in Canton Neuchatel, which at that time was 
under Prussian government. Neuchatel, from which ready 
access was afforded into the Jura mountains and into the Alps, 
now became his headquarters. Every observation was care- 
fully entered in his maps, and a number of scientific papers 
flowed from his ready and graceful pen. 

A visit to Auvergne in 1802, and a study of the basalt and 
trachyte in that area, still further shattered Von Buch's faith in 
Neptunian doctrines. In 1805 he was again at Naples, and in 
the company of Alexander von Humboldt and Gay Lussac he 
had the good fortune to witness Vesuvius in active eruption. 

Having explored the most interesting parts in Southern 
Europe, Von Buch then travelled for two years, 1 806-8, in 
Scandinavia and Lapland. The published account of his 
travels, Through Norway and Lapland^ established his fame 
as a gifted writer and an acute observer. Little had hitherto 
been known about the climatology and geology of these high 
European latitudes, and Von Buch contributed data of far- 
reaching significance. For example, he pointed out that 
although the rocks in these regions follow the same general 
scheme of succession as Werner had drawn up, the granite 
could by no means be regarded as the oldest rock-formation, 
since he had observed it near Christiania in a position above 
the Transitional Limestone. Again, he showed on mineral- 
ogical evidence that many of the erratic blocks scattered over 
the North German plains must have come from Scandinavia. 

Von Buch also examined the raised beaches and terraces of 
Scandinavia, and came to the conclusion that the Swedish 
coast was slowly rising above the level of the sea. In this he 
agreed with the opinion that had been formed by Playfair with 
regard to the raised beaches of Scotland. On the other hand, 
Linnaeus and Celsius had attributed the fluctuations on the 
Scandinavian coasts to a sinking of the water-level round the 

In 1809 Von Buch was chiefly engaged in mineralogical 
and geological researches in the Alps. Meanwhile, great 


interest had been roused throughout Europe by the results of 
Von Humboldt's brilliant volcanic studies in Central and 
South America, and Von Buch determined to make a special 
study of some volcanic district. 

Accompanied by the English botanist, Charles Smith, he 
visited the Canary Isles, and in 1815 convinced himself that 
they had been the centre of intense volcanic activity. In his 
famous monograph, A Physical Description of the Canary 
Islands, published in 1825, he enunciated his hypothesis of 
upheaval craters, and distinguished between "centres" and 
" bands" of volcanic action. In 1817 he travelled to Scotland 
and visited Staffa and the Giant's Causeway. When he again 
returned to the Alps, he renounced the Wernerian doctrines of 
the origin of basalt and other volcanic rocks, and ascribed the 
upheaval of the Alps to the intrusion of igneous rocks. About 
this time he went to Fassa Valley in South Tyrol, and there he 
formed a curious volcanic theory in explanation of the dolo- 
mitisation of the rocks in that district. 

In 1832 Von Buch edited a geological map of Germany, and 
this magnificent work had already run through five editions in 
1843. The last twenty years of his life were for the most part 
devoted to palaeontological studies, and we owe to this period 
a valuable series of papers on Cephalopods, Brachiopods, 
and Cystoids; also a comprehensive treatise on the Jurassic 
formation in Germany, which has been the basis for all 
future work on this subject. Some part of every year, 
however, was spent by Von Buch in travelling. He often 
went to the Alps, and he regularly attended the Scientific 
Congresses. Most of his Alpine journeys were accomplished 
on foot. Clad in short breeches, black stockings, and buckled 
shoes, the pockets of his black coat stuffed with note-books, 
maps, and geological tools, his tall, imposing figure was bound 
to command attention. His travelling luggage was limited to 
a fresh shirt and a pair of silk stockings. His physical en- 
durance was only surpassed by his iron determination, which 
could overcome all difficulties and discomforts. Socially, he 
was everywhere beloved; his aristocratic bearing, his mastery 
of foreign languages, his wide knowledge of science and 
literature, all combined to make him one of the most agree- 
able companions. His independent means placed him in a 
position of unusual influence. On the one side he enjoyed 
the friendship and intimacy of his scientific colleagues, and on 


the other he moved in the first social circle in Berlin. Men 
still live who can bear enthusiastic personal testimony to the 
noble way in which Von Buch exerted this influence for the 
benefit of science. After a short illness, he died in Berlin on 
the 4th March, 1852. 

Leopold von Buch was rightly regarded as the greatest 
geologist of his time. He had studied in every domain of 
geology; he was familiar with a large part of Europe. Wher- 
ever he went, he willingly and freely communicated his own 
knowledge to others, and ever rejoiced to be able to assist by 
his money or his influence any one in whom he detected a 
true devotion to science. At the same time he had little 
patience with men of mediocre ability, and was very severe 
towards importunity of any kind. His ridicule was feared as 
much as his praise was valued. He was an acute thinker and 
wonderful observer, and possessed in a high degree the rare 
gift of clear and elegant exposition. 

A complete edition of his works was published after his 
death at Berlin (1867-77). 

Alexander von Humboldt, the friend and fellow-student of 
Von Buch, although less illustrious as a geologist, had a more 
versatile and philosophical turn of mind. Like Von Buch, 
Humboldt belonged to an old aristocratic family. He was 
born in Berlin in 1769, studied at first in Gottingen, afterwards 
in 1791-92 with Werner at Freiberg. On the completion of 
his studies he was made Director of Mines, and moved from 
Bayreuth and Ansbach to Steben in the Fichtel mountains. 
Several papers written by him during this period on " The 
Magnetic Properties of Serpentine and other Rocks," attracted 
the attention of mineralogists. In 1793 he visited the salt 
mines in the Salzkammergut and Galicia, but in 1796 he 
resigned his Government appointment, to follow out inde- 
pendent lines of research. During the winter of 1797-98, when 
he and Von Buch lived together in Salzburg, he made a series 
of observations on meteorology and earth- magnetism, and 
took barometric and trigonometric measurements of height. 

In a treatise published in 1799, Von Humboldt endeavoured 
to explain the tropical climate of earlier geological periods by 
a combination of the Laplace theory of heat with Werner's 
views regarding the precipitation of the primitive rock 
materials from aqueous solutions. And although his treatise 
is almost forgotten in science, it contains a number of sug- 


gestive ideas which were not without their influence in directing 
subsequent investigation to the causes of great cliraatological 

Humboldt, who was in possession of large private means, 
now began to make arrangements for a few years of travel on a 
large scale, and went in May 1798 to Paris. In June 1799, 
accompanied by the botanist Aime Bonpland, he set out for 
Central and South America. 

The expedition was undertaken primarily to obtain more 
knowledge of the physical geography and botany of tropical 
regions, but Humboldt at the same time devoted a large share 
of attention to the volcanoes, earthquakes, and geological struc- 
ture of the New Continent. He said that one of the chief 
motives of his journey was to test a hypothesis which he had 
formed that the older strata composing mountain-systems 
had a parallel strike. It had struck him during his stay in 
the Fichtel mountains that the older members in the rock- 
succession showed always a N.E.-S.W. strike; and he found 
the same general strike in the Erz mountains, the Salzburg 
Alps, and the "slate" mountains of the Rhine. He had 
therefore concluded that all the older rock-formations of the 
earth strike in N.E.-S.W. direction, and cross the meridians at 
a constant angle of about 52. 

His observations in Columbia and in the coastal ranges of 
the Gulf of Mexico led to the same result, and from this agree- 
ment he drew the general principle that the strike of the older 
strata was quite independent of the geographical trend of 
mountain-systems, and was regulated by a force which took its 
origin in the original laws of attraction governing terrestrial 
matter. This principle has, however, proved quite untenable, 
and is at the present day completely forgotten. 

After a short stay in Teneriffe, Humboldt landed at Vene- 
zuela, and in November 1799 for the first time witnessed an 
earthquake at Cumana. He made a detailed study of 
Venezuela, then spent some time in the Orinoco district, and 
was in Cuba from December 1800 until March 1801. After- 
wards he proceeded to New Granada, Peru, and Ecuador, 
where he remained until 1803, then worked for a year in 
Central America. In the summer of 1804 he returned by 
Havana and North America to Paris. There he became at 
once absorbed in physical and chemical studies, conducted 
along with Biot, Gay Lussac, and Arago, and he also com- 



menced the publication of his great work, Travels in the 
Equinoctial Regions on the New Continent. This work com- 
prises twenty volumes ; but although there were several 
collaborators, the work was never quite completed, and the 
expenses in connection with it swallowed up the remainder of 
Von Humboldt's means. In the spring of 1805 he visited 
Italy, and with his friends, Gay Lussac and Leopold von 
Buch, saw an eruption of Vesuvius. 

Humboldt's best contributions to geology were his investiga- 
tion of volcanoes and earthquakes, and the broad generalisations 
which he drew regarding volcanic action. He concluded 
his description of American volcanoes with a review of all 
the volcanic phenomena known to have transpired on the 
face of the earth, and tried to demonstrate, from a large number 
of observations, that the subterranean centres of volcanic action 
are in direct communication with one another. He placed 
great importance upon the connection of volcanoes and earth- 
quakes on the coasts of the Gulf of Mexico and in the Antilles, 
where subterranean disturbances were felt almost simultaneously 
over a district several thousand square miles in extent. Hum- 
boldt's account of the catastrophe in the year 1759, which gave 
birth to the Jorulla and five other mountains, and covered an 
area, of four square miles with a mass of lava, sand, and slag 
five hundred feet high, still ranks as one of the most note- 
worthy contributions in the whole literature of volcanoes. 

Widespread interest in scientific circles was also attracted by 
Humboldt's demonstration of an eruptive fissure one hundred 
and fifty miles from east to west across Central America, upon 
which stand the volcanic cones of Tuxtla, Orizaba, Puebla, 
Toluca, Tancitaro, and Colima. 

Through the generosity of the King of Prussia, Humboldt 
was enabled to devote his energies to science. During nearly 
twenty years' residence in Paris (1808-27) he published the 
series of papers which form the groundwork of his Views of 
Nature, and also a special geological work entitled Geognostic 
Essay on the Trend of the Rocks in the Tivo Hemispheres ( Paris, 
1822). This work practically marked the conclusion of Hum- 
boldt's literary activity in geology. Upon his return to his 
native city of Berlin in 1827, Humboldt embarked upon his 
gigantic plan of producing a physical description of the world. 
Twenty years passed before this plan was realised and his 
famous work, The Cosmos, appeared. While the work was in 


progress Humboldt led an active life in other directions. In 
1827-28 he gave lectures on geography in the University and 
the Singing Academy. In 1829, accompanied by Gustav Rose 
and Ehrenberg, he travelled through Asiatic Russia, the Ural 
mountains, and Siberia to the Altai mountains. The mineral- 
ogical and geological results of this journey were published in an 
independent work by Humboldt, and in several papers by Rose. 

Alexander von Humboldt died at Berlin on the 6th May 
1859, in his ninetieth year. 

Although many of the geological ideas of the great German 
scientist were not destined to endure, it is impossible to over- 
rate the value to geographical and geological science of the 
precedents which he created, and the wide horizons which he 

What Buffon and Cuvier accomplished for France in attract- 
ing the ardent desires of young adherents to the studies of 
natural science, was accomplished for Germany, after the death 
of Werner, by the powerful personalities of Leopold von Buch . 
and Alexander von Humboldt. 

It is interesting to note that Germany's greatest poet, Wolf- 
gang von Goethe, was one of those who came under the 
inspiring influence of Werner. Throughout his long life 
Goethe never lost his interest in mineralogy and geognosy. 
He wrote several papers on the more popular topics of 
geognosy, and carried out some detailed researches in the 
neighbourhood of Karlsbad, Franzensbad, and the Fichtel 
mountains. While he never could, as a loyal pupil of Werner, 
look kindly upon the principles of the Plutonists, his critical 
mind clearly realised that the theories of extreme Neptunists 
were untenable. In his Geological Problems he expressed his 
disappointment over the absurd contradictions betrayed in the 
opposing theories, but arrived at no personal decision in favour 
of either party. Goethe's geological writings were without 
significance in the progress of the science. 

^ Playfair, and HalL At a time when Werner was 
in the zenith of his fame, during those seventies and eighties 
of the eighteenth century when young geologists were flocking 
to hear the wisdom from the lips of the prophet of geognosy in 
Freiberg, a private gentleman, living quietly in Edinburgh, was 
deliberating and writing a work on the earth's surface that will 
live for ever in the annals of geology as one of its noblest classics. 


James Hutton, the author of the famous Theory of the Earth, 
was the son of a merchant, and was born in Edinburgh on 
3rd June 1726. He received an excellent education at the 
High School and University of his native city. His strong 
bent for chemical science induced him to select medicine as a 
profession. He studied at Edinburgh, Paris, and Ley den, and 
took his degree at Leyden in 1749, but on his return to 
Scotland he did not follow out his profession. Having in- 
herited an estate in Berwickshiie from his father, he went to 
reside there, and interested himself in agriculture and in 
chemical and geological pursuits. The success of an industrial 
undertaking in which he had a share afforded him ample 
means, and in 1768 he retired to Edinburgh, where he lived 
with his three sisters. He actively engaged in scientific inquiry, 
and enjoyed the cultured social intercourse open to him in 
Edinburgh. The literary fruits of his life in the country 
include several papers on meteorology and agriculture, and a 
large philosophical work. 

From his early days he had always taken a delight in study- 
ing the surface forms and rocks of the earth's crust, and had 
lost no opportunity of extending his geological knowledge 
during frequent journeys in Scotland, England, in Northern 
France, and the Netherlands. On his tours into the neigh- 
bourhood of Edinburgh he was often accompanied by his 
friends, who realised the originality of many of Hutton's views 
on geological subjects, and begged him to put them into 
writing. At last Hutton set himself to the work of shaping 
his ideas into a coherent, comprehensive form, and in 1785 
read his paper on the " Theory of the Earth " before the Royal 
Society of Edinburgh. Three years later it was published in 
the Transactions. 

The publication of the work attracted little favourable notice. 
This may have been due partly to the title, which was the 
same as that of so many valueless publications, and partly to 
the involved, unattractive style of writing; in larger measure, 
however, it was due to the fact that the learning of the schools 
had no part in Hutton's work. Hutton's thoughts had been 
borne in upon him direct from nature; for the best part of his 
life he had conned them, tossed them in his mind, tested them, 
and sought repeated confirmation in nature before he had even 
begun to fix them in written words, or cared to think of any- 
thing but his own enjoyment of them. 


Mutton's work was projected upon a plane half a century 
beyond the recognised geology of his own time. Hutton's 
audience of geologists had to grow up under other influences 
than polemical discussions between Neptunists and Plutonists, 
and had to learn from Hutton himself how to tap the fountain 
of science at its living source. 

In 1793 a Dublin mineralogist, Kirwan, attacked Hutton's 
work in ignoble terms, and the great Scotsman, now advanced 
in years, resolutely determined to revise his work and do his 
best by it. Valuable additions were made, and the subject- 
matter brought under more skilful treatment. In 1795 the 
revised work appeared at Edinburgh, in independent form and 
in two volumes. It was his last effort. Hutton died in 1797 
from an internal disease which had overshadowed the closing 
ypafs of his life. 

The original treatise of Hutton is divided into four parts. 
The first two parts discuss the origin of rocks. The earth 
is described as a firm body, enveloped in a mantle of water 
and atmosphere, and which has been exposed during im- 
measurable periods of time to constant change in its surface 
conformation. The events of past geologic ages can be most 
satisfactorily predicted from a careful examination of present 
conditions and processes. The earth's crust, as far as it is 
open to our investigation, is largely composed of sandstones, 
clays, pebble deposits, and limestones that have accumulated 
on the bed of the ocean. The limestones represent the 
aggregated shells and remains of marine organisms, while the 
other deposits represent fragmental material transported from 
the continents. In addition to these sedimentary deposits of 
secondary origin there are primary rocks, such as granite and 
porphyry, which, as a rule, underlie the aqueous deposits. 

In earlier periods the earth presented the aspect of an 
immense ocean, surmounted here and there by islands and 
continents of primary rock. There must have been some 
powerful agency that converted the loose deposits into solid 
rock, and elevated the consolidated sediments above the 
level of the sea to form new islands and continents. 

According to Hutton, this agency could only have been v 
heat ; it could not have been water, since the Cement J 
material (quartz, felspar, fluorine, etc.) of many sedimentary ' 
rocks is not readily soluble in water, and could scarcely have 
been provided by water. On the other hand, most solid rocks 


are intermingled with siliceous, bituminous, or other material 
which may be melted under the influence of heat. This 
suggested to Hutton his theory that at a certain depth the 
sedimentary deposits are melted by the heat to which they are 
subjected, but that the tremendous weight of the super- 
incumbent water causes the mineral elements to consolidate 
once more into coherent rock-masses. He applied this theory 
]of the melting and subsequent consolidation of rock-material 
{universally, to all pelagic and terrestrial sediments. 

In the third part it is shown that the present land-areas of 
the globe are composed of rock-strata which have consolidated 
during past ages in the bed of the ocean. These are said to 
have been pushed upward by the expansive force of heat, 
while the strata have been bent and tilted during the 
upheaval. Hutton next describes the occurrence of crust- 
fissures both during the consolidation of the rock and during 
the elevation of large areas, and the subsequent inrush of 
molten rock or mineral ores into the fissures. He regards 
volcanoes as safety-valves during upheaval, which by affording 
exit at the surface for the molten rock-magma and superheated 
vapours prevent the expansive forces from raising the con- 
tinents too far. 

The evidences of volcanic eruption in the older geological 
epochs are next discussed. Hutton expresses the opinion 
that during the earlier eruptions the molten rock-material 
spread out between the accumulated sediments or filled crust- 
fissures, but did not actually escape at the ^surface ; con- 
sequently, that the older rock-magmas had solidified at great 
depths in the crust and under enormous pressure of 
superincumbent rocks. He calls the older eruptive rocks 
"subterraneous lavas" and includes amongst them porphyry 
and the whinstones (eq. trap-rock, greenstone, basalt, wacke, 
amygdaloidal rocks) ; granite was also added in a later treatise. 
Hutton points out that the subterraneous lavas have a 
crystalline structure, whereas those that solidify at the 
surface have a slaggy or vesicular structure. 

In the fourth part, Hutton concentrates attention on the 
pre-existence of older continents and islands from which the 
materials composing more recent land areas must have been 
derived. He likewise discusses the evidences of pre-existing 
pelagic, littoral, and terrestrial faunas from which existing 
faunas must have sprung. But, he continues, the existence of 


ancient faunas assumes an abundant vegetation, and direct 
evidence of extinct floras is presented in the coal and 
bituminous deposits of the Carboniferous and other epochs. 
Other evidence is afforded in the silicified trunks of trees that 
occasionally are found in marine deposits, and have clearly 
been swept into the sea from adjacent lands. 

Hutton then sets forth, in passages that have become classic 
in geological science, the slow processes of the subaerial denuda- 
tion of land-surfaces. He describes the effects of atmospheric 
weathering, of chemical decomposition of the rocks, of their 
demolition by various causes, and the constant attrition of the 
soil by the chemical and mechanical action of water. He 
elucidates with convincing clearness the destructive physical, 
chemical, and mechanical agencies that effect the dissolution 
of rocks, the work of running water in transporting the worn 
material from the land to the ocean, the steady subsidence of 
coarser and finer detritus that goes on in seas and oceans, lakes 
and rivers, and the slow accumulation of the deposits to form 
rock-strata. Hutton impresses upon his readers the vastness 
of the geological seons necessary for the completion of any 
such cycle of destruction and construction. In proof of this, 
he calls attention to the comparative insignificance of any 
changes that have taken place in the surface conformation of 
the globe within historic time. 

Hutton was thus the great founder of physical and dynamical 
geology; he for the first time established the essential correla- 
tion in the processes of denudation and deposition; he showed 
how, in proportion as an old continent is worn away, the 
materials for a new continent are being provided, how the'' 
deposits rise anew from the bed of the ocean, and another land j 
replaces the old in the eternal economy of nature. The out-/ 
come of Hutton's argument is expressed in his words {C that wej 
find no vestige of a beginning, no prospect of an end." 

When we compare Hutton's 'theory of the earth's structure 
with that of Werner and other contemporary or older writers, 
the great feature which distinguishes it and marks its superiority, 
is the strict inductive method applied throughout. Every! 
conclusion is based upon observed data that are carefully' 
enumerated, no supernatural or unknown forces are resorted to, 
and the events and changes of past epochs are explained from 
analogy with the phenomena of the present age. 

The undeveloped state of physics and chemistry in the time 


of Hutton certainly gave rise to several errors in connection 
with the origin of minerals and rocks. No geologist now 
would agree with the principle that heat has hardened and 
partially melted all sedimentary rocks, and just as little would 
he ascribe to heat the origin of flint, agate, silicified wood, etc. 
On the other hand, the recognised hypothesis of regional 
metamorphism of the crystalline schists is an extension of 
Mutton's conception of the action of heat and pressure upon 

Hutton was the first to demonstrate the connection of 
eruptive veins and dykes with deeper-seated eruptive masses of 
granite, and the first to point out the differences of structure 
between superficial lavas and molten rock solidified under great 
pressure. In assuming that granite represents rock consoli- 
dated from a molten magma, Hutton laid the foundation of the 
doctrines of Plutonism as opposed to those of Neptunism. 

Again, no one before Hutton had demonstrated so effectively 
and conclusively that geology had to reckon with immeasurably 
long epochs, and that natural forces which may appear small 
can, if they act during iDng periods of time, produce effects 
just as great as those that result from sudden catastrophes of 
short duration. 

Hutton's explanation of the uprising of continents, owing to 
the expansive force of the subterranean heat, was not altogether 
new, nor was it satisfactory. Neither had Hutton any clear 
conception of the significance of fossils as affording evidence 
of a gradual evolution in creation. Yet in spite of these dis- 
advantages, Hutton's Theory of the Earth is one of the master- 
pieces in the history of geology. Many of his ideas have been 
adopted and extended by later geologists, more particularly by 
Charles Lyell, and form the very groundwork of modern 
geology. Hutton's genius first gave to geology the conception 
of calm, inexorable nature working little by little by the rain- 
drop, by the stream, by insidious decay, by slow waste, by the 
life and death of all organised creatures, and eventually 
accomplishing surface transformations on a scale more gigantic 
than was ever imagined in the philosophy of the ancients or 
the learning of the Schools. And it is not too much to say 
that the Huttonian principle of the value of small increments 
of change has had a beneficial, suggestive, and far-reaching 
influence not only on geology but on all the natural sciences. 
The generation after Hutton applied it to palaeontology, and 


thus paved the way for Darwin's still broader, biological con- 
ceptions upon the same basis. 

Hutton's scientific spirit and genial personality won for him 
many friends and adherents amongst the members of the 
Edinburgh academy. The most distinguished of these were 
Sir James Hall and the mathematician John Playfair. 
Hall (1762-1831) contested the validity of the opinion held by 
some of Hutton's opponents, that the melting of crystalline 
rocks would only yield amorphous glassy masses. Hall 
followed experimental methods; he selected different varieties 
of ancient basalt and lavas from Vesuvius and Etna, reduced 
them to a molten state, and allowed them to cool. At first he 
arrived only at negative results, as vitreous masses were pro- 
duced; but he then retarded the process of cooling, and 
actually succeeded in obtaining solid, crystalline rock-material 
(Nicholson's Journal, No. 38, 1800). By regulating the tem- 
perature and the time allowed for the cooling and consolidation, 
Hall could produce rocks varying from finely to coarsely 
crystalline structure. And he therefore proved that under 
certain conditions crystalline rock could, as Hutton had said, 
be produced by the cooling of molten rock-magma. Hall then 
put to the test Hutton's further hypothesis, that limestone also 
was melted and re-crystallised in nature. To this hypothesis 
the objection had been made that the carbonic acid gas must 
escape if limestone were brought to a glowing heat, and the 
material would be converted into quicklime. This was Hall's 
first experience; then he devised another experiment. He 
introduced chalk or powdered limestone into porcelain tubes 
or barrels, sealed them, and brought them to a very high 
temperature. The carbon dioxide gas could not escape under 
these conditions. The calcareous material was thus subjected 
to the enormous pressure of the imprisoned air, and carbonic 
acid was converted under this pressure into a granular substance 
resembling marble. Hall calculated from a series of successful 
experiments that a pressure equivalent to fifty-two atmospheres, > 
or to a depth of sea-water 1,700 feet below sea-level, was neces- 
sary for the production of solid limestone, 3000 feet of depth for 
that of marble, and 5,700 feet of depth in order to reduce 
carbonate of lime to a molten state. 

These results were afterwards confirmed by other experi- 
mentalists. Thus Werner's theory that crystalline rock repre- 
sented in all cases a precipitate from water was shown to be 


inadequate, and it was incontestably proved that crystalline 
rock might originate from molten rock when slowly cooled 
under pressure. 

Hall also conducted experiments on the bending and folding 
of rocks. He spread out alternate horizontal layers of cloth 
and clay, placed a weight upon them, and subjected them to 
strong lateral pressure. These and similar experiments have 
been often repeated within recent years, and it is well known 
that in this way phenomena of deformation can be artificially 
produced which bear the closest resemblance to the phenomena 
of rock-deformation under natural conditions. 

Hall, in his desire to vindicate Hutton's theory, became 
himself one of the great founders of experimental geology. 
At the same time, John Playfair, 1 whose interest in geology 
had been roused by Hutton's companionship, became the 
enthusiastic exponent of Hutton's theory. 

It was Playfair's literary skill that opened the eyes of scien- 
tific men to the heritage Hutton had left for them. He did 
for Hutton's teaching what fifty years after was done for 
Darwin's doctrines by the gifted Huxley. The brilliant ex- 
ponent and successful combatant, no less than the deep 
student and enlightened thinker, is required to establish a new 
system of thought, for such a system is always, bound to be in a 
measure reactionary to older doctrines that have received the 
stamp of usage and authority. 

Playfair's Illustration of the Huttonian Theory (1802) is a 
lucid exposition of that theory in the form of twenty-six ample 
discussive notes. Playfair's work differs in no essential point 
from the views held by his master and friend, but many 
subjects which receive a subordinate treatment in the Theory 
of the Earth are brought into prominence by Pbyfair, and 
placed for the first time on a firm scientific basis. 

Among the subjects fully discussed are the uprise and 
bending of strata, the origin of crystalline rocks at low 

1 John Playfair, born 1748, in Bervie, Forfarshire, son of a minister, 
showed in his early years a remarkable genius for mathematics. He 
studied in Aberdeen and Edinburgh, in 1773 became minister in Bervie, 
in 1785 Professor of Mathematics in the University of Edinburgh, and 
twenty years after Professor of Philosophy in the same University. Led 
by Hutton into the study of geology, he devoted his holidays to geological 
tours throughout Great Britain and Ireland, and in 1815 and 1816 made 
longer tours to Auvergne, Switzerland, and Italy; he died in 1819 in 


horizons of the crust and under very great pressure, and the 
occurrence of granite as dykes in various British localities. 
His treatment of valley and lake erosion is extremely able. 
And Playfair was the first geologist who realised that the huge 
erratic blocks might have been carried to their present position by 
former glaciers. His insight in this respect would alone have 
won for him a lasting fame, for the erratics on Alpine slopes 
and plains had long been observed by geologists and an 
explanation vainly sought. Playfair also studied the raised 
beaches on the coast-line of Scotland, and rightly concluded 
that they afforded evidence of an actual uprise of the land, in 
opposition to the views of Linnaeus and Celsius, who had 
explained a similar series of phenomena in Sweden as a result 
of the retreat of the ocean. Playfair gave the first complete 
account of the evidences of oscillations of level in European 

Playfair's style is a model of clearness and precision, and 
his arguments are always thoroughly logical, and in agreement 
with physical laws. His Huttonian Theory was translated into 
French by C. A. Basset in 1815. 

Theories of the Earth's Origin proposed by De Luc, De la 
Melherie, Breislah, Kant, Laplace, and others. Although 
Hutton had enunciated his theory of the earth without 
introducing any personal element, it was a foregone conclusion 
that a doctrine which undermined the whole foundation of 
Werner's Neptunian teaching, was bound to meet with adverse 
criticism. Mention has already been made of the attacks 
made by Kirwan, Professor of Mineralogy in Dublin (Geo- 
logical Essays, 1799). His arguments are based upon 
chemical and physical objections to Hutton's theory, and 
culminate in a bitter denunciation of a theory inimical to 
religion, and at variance with the Mosaic account, inasmuch 
as it demanded immeasurable epochs in place of the Biblical 
chronology, and even denied the universal deluge, to which 
Kirwan mainly ascribed the present configuration of the earth. 

Another antagonist of Hutton's theory was the versatile 
Jean Andre de Luc, a Genevese by birth, who came into 
public notice during the political struggles in Geneva in the 
middle of the last century, and afterwards attained to a 
favoured position in the court of Queen Charlotte of England. 
De Luc wrote on all manner of scientific subjects, and his 


great desire was to bring the facts of science into complete 
and unquestionable harmony with the words of Holy Writ. 

A special interest is attached to De Luc's Letters on some 
parts of Switzerland, which were originally addressed to 
Queen Charlotte, and were afterwards published in 1778. In 
the preface to these letters he proposes the term Geology as 
the most suitable for a scientific study purporting to deal with 
the history of the earth. The preface is written in bombastic 
style, announcing that a new outline of cosmology and geology 
would be enunciated by the writer. The Letters themselves 
contain little that could be supposed to bear out the high 
promises of the preface, but a year later De Luc's theory 
appeared in a work of five volumes, entitled Physical and 
Moral Letters on the History of the Earth and of Man, The 
moral discourses are comprised in the first part of the work. 
Then the scientific letters begin with a resume of the theories 
of the earth's origin constructed by Burnet, Whiston, Wood- 
ward, Leibnitz, Scheuchzer, and others, all of which are found 
erroneous and set aside by De Luc. He then describes his 
travels in different parts of Europe, and records any geological 
observations he had made. 

He states his reasons for disbelieving in the enormous 
erosive activity which contemporaneous writers ascribed to 
water. And he strongly expresses himself in favour of the 
eruptive origin of basalt, as against the ideas held by Werner's 
school. The fifth volume is that in which De Luc unfolds his 
own theory. He distinguishes primordial mountains com- 
posed of rocks of unknown origin, such as granite, schist, 
serpentine, quartzite from secondary mountains, composed of 
stratified deposits containing fossils, and clearly of aqueous 
origin. As there are terrestrial plants and animals among the 
fossils of the "secondary mountains," De Luc supposes that, 
although the ocean must have originally covered the earth's 
surface, there must have been land areas at the time when the 
strata of the "secondary mountains" were deposited. The 
floor of this restricted ocean was, he said, formed by the 
"primordial mountains," but in the heart of these mountains 
there were cavities of irregular shape disposed tier upon tier 
above one another, so that the firm rock merely formed a 
scaffolding. Owing to subterranean fire or any other disturbing 
cause, it sometimes happened that the rock pillars in these 
hollow areas gave way, and crust-inthrows ensued. The 


increasing weight of the deposits, which were accumulating on 
the ocean-floor, as well as the pressure caused by the repeated 
crust-inthrows, at last caused the collapse of the lower tiers. 
The sea-water rushed in to fill the depressed areas, and the 
level of the ocean sank. This was called the first revolution 
in De Luc's sequence of creative events. As the ocean sank, 
the present continents and islands made their appearance; 
plant seeds from the old continents were washed on the 
strands of the emerging lands, and soon a rich vegetation 
appeared. The fauna of the primitive ocean and lands in 
some cases left descendants to people the new oceans and 
lands, in other cases became extinct. 

The bones of the large tropical mammalia found in the 
superficial strata of northern areas in the present continents 
were believed by De Luc to be the transported remains of 
extinct forms that had inhabited the older continents. Ac- 
cording to De Luc, all known facts led to the conclusion that 
the new continents, and generally the present configuration of 
the earth, came into existence not more than 4000 years 

Four letters protesting against both Hutton and Playfair were 
reprinted in a diffuse work by De Luc, entitled Elementary 
Treatise of Geology. A large number of papers were con- 
tributed to journals by De Luc ; but although he was a man 
who was held in high respect and favour during his lifetime, 
his papers have no permanent place in literature, and his 
attacks on the great Scottish geologists were absolutely without 

Like De Luc, the Parisian mineralogist and physician, De 
la Metherie, enjoyed considerable popularity among his con- 
temporaries. His chief work, published at Paris in 1791, bore 
again the title Theorie de la Terre. De la Metherie's work was 
founded for the most part on Werner's teaching. Many of 
the erroneous notions in De Maillet's Telliamed were revived 
and new speculations attempted, but without any basis of 
observation. According to De la Metherie, all mountains, 
valleys, and plains took origin from the precipitation of 
crystals in a primeval ocean which covered the whole earth, 
and was of enormous depth. During the accumulation of 
rock-precipitates certain large subterranean cavities filled with 
air or vapour remained free from solid deposits. As the total 
volume of water diminished, a considerable portion of the 


sea withdrew into these crust-cavities, and at the same time 
the areas of denser precipitation became land. Volcanic 
eruptions invariably originated in these primitive air and vapour 
chambers in the earth's crust, which were moreover frequently 
connected with one another by crust-fissures. 

It is unnecessary to enter into the further details of De 
la Metherie's Theory. Two years after its publication, 
Bertrand, another French geologist, wrote New Principles of 
Geology*^ a work contesting De la Metherie's conceptions, but 
not in itself contributing any new facts of value to science. 
Ballenstedt, a German pastor, was the author of a book 
entitled Die Urwelt (or the Primeval World\ which was 
widely read in scientific and literary circles. It endeavoured 
to " expound the Biblical stories in a sensible way," and went 
so far as to affirm that all human races had not descended 
from the one pair in Paradise, but that there had been 
originally several well-defined human species. 

Scipio Breislak (1748-1826), an Italian, deserves to be 
remembered for his determined opposition to the Neptunian 
doctrines. In his Text-book of Geology he tries to demon- 
strate that the earth was originally in a fluid state, but that the 
volume of water now present on the globe would be absolutely 
insufficient to dissolve the solid material of the crust. 

Further, the presence in earlier epochs of a much greater 
volume of water was a mere hypothesis, so also was the con- 
ception of internal crust-cavities into which large quantities of 
water might have withdrawn after the separation of the rock- 
precipitates. Again, there was no positive evidence that the 
surface of the ocean had sunk. The cases of apparent retreat 
of the sea from the coasts of Scandinavia, or in the Gulf of 
Naples, might be just as well explained by oscillatory move- 
ments of the earth's crust as by the supposed general lowering 
of the sea-level. After Breislak had demonstrated the im- 
possibility of a fluid state of the earth with water as the 
solvent, he tried to prove that the primitive fluidity of earth 
substances had been due to their intimate admixture and 
combination with heat-particles. Breislak imagines the earth 
in its first periods of formation as a confused cosmic mass 
soaked in heated matter, and therefore more or less molten. 
Two modes of heat are distinguished by Breislak, free heat, 
which calls forth the sensation of heat, and combined heat, 
which is not perceptible to the senses, but whose combination 


with other forms of matter effects important changes. Upon 
this physical basis, Breislak supposes that, as the heat-particles 
entered into combination with other particles of matter for 
which they had affinity, the total amount of free heat 
diminished, and the temperature of the earth perceptibly 
cooled. Gaseous material gathered internally and still more 
at the surface, where it was condensed as a primitive ocean. 
The internal gases in combination with heat produced elastic 
vapours. These tried to force their way to the surface, 
cracking and breaking the solid crust that had begun to 

Breislak then discusses the origin of the various kinds of 
crystalline rock found in the crust. He disagrees with 
Hutton's explanation of gneiss and crystalline schist as 
altered sedimentary rock, and includes them together with 
granite, porphyry, and other igneous rocks, as products of the 
cooling of matter from the primitive molten state. Breislak's 
ideas about rock-structure soon fell into oblivion, but his able 
criticism of the Neptunian dogmas was largely instrumental in 
eradicating them from the teaching of the universities and 
colleges. There would be little profit in recording further 
the many contradictory theories of the earth that appeared 
between the publication of Buffon's Theorie de la Terre in 
1749 and of Breislak's Introduzione alia Geologia in 1811. 
What seems very remarkable is that in none of these can we 
trace the influence of the cosmogony and geogeny made known 
in 1755 by the great philosopher, Immanuel Kant, in his 
Naturgeschichte des Himmels. Neither do geologists seem 
to have benefited by the kindred work of the French mathe- 
matician, Laplace, Exposition du Systeme du Monde, published 
in 1796. 

Kant's little book appeared anonymously, immediately before 
the outbreak of the Seven Years' War. It received no atten- 
tion, was forgotten, and ninety years elapsed before Alexander 
von Humboldt unearthed it from neglect. Kant originated 
the conception that the ordered cosmical universe might have 
been produced merely by the agency of mechanical forces 
acting upon a vaporous chaotic mass. Kant supposed that all 
the matter composing the spherical bodies of our solar system, 
the planets and the comets, was in the beginning broken up 
into its elementary constituents and distributed throughout 
space. All the particles of matter could attract and repel one 


another ; the equilibrium of matter was in a highly fickle and 
unstable condition. The denser particles of matter tended, by 
reason of their attractive force, to unite into a central body. 
At the impact the particles were diverted by the disturbing 
action of the attractive and repulsive forces ; there arose 
numerous whirls of movement crossing one another. The 
particles in these whirls or vortices originally moved in all 
directions, and were constantly coming into conflict with one 
another, but finally the movements became uniform in direc- 
tion, and the particles revolved almost in one heavenly plane, 
and without mutual disturbance in concentric circles round the 
sun. Within each individual ring the attraction of the particles 
again came into play, aggregates of the denser particles attracted 
the lighter particles in the same ring until a planetary body 
formed, revolving round the sun along its particular path. In 
this way the whole planetary system, including moons and 
comets, was thought by Kant to have taken origin in order 
according to the distance of the path of revolution from the 
sun ; first, the planets next the sun, then those more remote 
from the sun. 

While Kant's mechanical theory of the universe explains the 
origin of all the bodies in the solar system upon the same 
fundamental principle, it yields no exact information regarding 
the constitution and the temperature of the sun and the planets. 
The nebular theory of Laplace, which was founded quite inde- 
pendently of Kant, goes further in this respect, and has therefore 
come into closer relationship with geology. 

Laplace shows that all the planets in the solar system move 
round the sun from west to east in almost the same plane, that 
all moons move in similar direction round their planets, and 
that the sun rotates, so far as is known, in the same direction 
round its own axis. In the opinion of the great mathematician, 
a phenomenon so remarkable cannot be mere chance, but 
indicates some general cause or combination of causes that 
has determined all those movements. Clearly, there was a 
time when the planetary spaces now empty were uniformly 
filled with matter at a high temperature, representing the sub- 
stances of the planets and moons in the finest state of 
rarefaction, and having a rotating movement from west to 
east. A central body, the sun, massed itself in the midst of 
this vaporous material. 

The finely divided mass behaved like a gigantic atmosphere, 



in which equilibrium was sustained by centrifugal force and 
gravity. As the glowing mass became denser the centri- 
fugal force increased, and peripheral rings of vapour similar to 
those of Saturn separated from the main body. The detached 
rings continued to move with the same rate and direction of 
motion as before. Not being of uniform density, they became 
rent, the different masses formed themselves into rotating 
spheres, the larger bodies absorbed a part of the smaller, and 
thus the planets and their satellites took origin. 

The condensation of the vaporous material during the 
process of aggregation of the particles into spheroids set free 
a large amount of heat and the newly-formed bodies were 
raised to a very high temperature; they became radiant 
masses, radiating light and heat into surrounding space. 
Owing to the loss of heat by radiation, the surface cooled and 
shrivelled, and finally a superficial crust formed, at first 
glowing, afterwards darkening down to its present state. 

According to Laplace, the zodiacal light represents certain 
volatile unconsolidated parts of the solar atmosphere that still 
surround the sun ; while the comets are regarded by Laplace 
as foreign to the solar atmosphere, belonging probably to the 
infinite space beyond. 

The nebular theory of Kant and Laplace was in far better 
agreement with the laws of mechanics and the observations of 
astronomy than any previous cosmogonetic hypothesis. It 
also helped greatly to elucidate the earliest beginnings of the 
earth, and was welcomed by geologists. Clearly it brought 
confirmation to Volcanistic doctrines, and militated against 
the Neptunian teaching that the primitive crystalline rocks 
were of aqueous origin. 

Local Geognostic Descriptions and Stratigraphy. A. Ger- 
many. The revolutionary tendency of the empirical methods 
taught by Werner in his system of geognosy is displayed in the 
numerous local monographs that began to appear in all parts 
of Europe. Both in mineralogy and in stratigraphy, the chief 
contingent of new work came from the Wernerian school. 

Georg Lasius (1752-1833), who for a long time held the 
post of Director of the Survey Department in Oldenburg, was 
no Wernerian, but he contributed a work on the Harz district 
that ranks among the best and most careful local descriptions 
of his time. While Lasius was an officer in the Hanoverian 



Engineer Corps, the duty of preparing the topographical map 
of the Harz was entrusted to him. From this beginning, 
Lasius became interested in the structural relations, and 
prepared a work which was published in two volumes, 
Observations on the Harz Mountains^ together with a petro- 
graphical map and a section (Hanover, 1789). 

In the first volume, Lasius describes the "primitive rocks" 
(Ur-gebirge) and the "vein-series" (Gang-gebirge), &n& places 
these groups in contradistinction to the " Flotz formations " or 
younger stratified deposits. The "vein-series" comprises 
marine limestones with corals, orthoceratites, bivalves, and 
gastropods ; slates, greywackes, and sandstones ; trap-rock, 
porphyry, and serpentine. The distribution of the various 
kinds of rock is entered with great accuracy upon a coloured 
petrographical map, and the term greywacke is used for the 
first time in the literature for a sandstone made up of finely 
fragmental granite debris. 

Lasius follows Lehmann for the most part in his sub-divi- 
sions of the Flotz deposits ; he shows, however, that a part of 
the porphyry occurs in association with the Red Sandstones of 
Permian age, and must therefore be younger than the main 
body of the vein series. 

The second volume of the work is devoted to a description 
of the ores and minerals in the Harz mountains, and contains 
many new and valuable observations. 

The Thuringian Forest was made the subject of several 
excellent geological works by an eminent scholar of Werner, 
Johann Karl Wilhelm Voigt (1752-1821). Trained for the law, 
Voigt gave up this profession, became an ardent geologist, 
and held the post of Councillor of Mines at Ilmenau in 

Voigt's work, in two volumes, entitled Mineralogical Journey 
through the Duchy of Weimar and Eisenach, was published 
between 1781 and 1785. Like many of his contemporaries, 
Voigt wrote this work in the form of letters. It contained 
what was at the time rather exceptional, a series of geological 
sections. Another work, which was undertaken by Voigt at 
the desire of Bishop Henry, gives a mineralogical description 
of the district around the monastery of Fuld. The basalt and 
phonolite rocks in the neighbourhood are accurately entered 
in a coloured geological map, and the text is remarkable for 
Voigt's tacit renunciation of Werner's views about the origin 


of these rocks, and his clear exposition of their volcanic 

After the publication in 1 788 of Werner's work on the 
occurrence of basalt at the Scheibenberg Hill, the difference 
of opinion between these two geologists began to assume a 
more personal aspect, and unfortunately ended in a rupture 
of their friendship. 

Voigt published several important papers on the geology of 
Thuringia in later years, chiefly in mineralogical journals, and 
he was also the author of the first practical Text-book of 
Geognosy (Weimar, 1792). In the description of the rocks 
and the order of rock-formations in the crust, Voigt follows 
Werner's teaching, but he has a more just appreciation of the 
causes of volcanic phenomena and the origin of volcanic 

His last large work was entitled Attempt at a History of 
Coal, Brown Coal and Turf (Weimar, 1802-5). This con- 
tains, in addition to the geological data, practical advice on the 
determination of workable coal-seams, and the industrial uses 
of the various kinds of combustible deposits. 

A detailed account of several localities in the Thur- 
ingian Forest was also given by Johann Ludwig Heim, a 
Privy Councillor in the Duchy of Meiningen. Heim (1741- 
1819) was tutor to the Princes of Meiningen, and during 
occasional journeys he made a large mineralogical collection, 
and wrote a number of papers compiled into one larger work, 
Geological Descriptions of the Thuringian Forest (Meiningen, 
1796-1812). These are distinguished by the independence 
of his views, acute powers of observation, and his clear 
descriptions; but there is no geological map, and the 
stratigraphical details are only illustrated by rough sketches. 
Hence the work, careful though it was, never received much 
recognition, and was much less instructive in character than 
that of Voigt. 

Heim referred the origin of the primitive rocks to chemical 
crystallisation from an indefinite mixture or "fluidum," 
possibly gaseous in constitution. He allowed that the slates 
and greywackes ("transitional rocks " of Werner) might have 
been precipitated from a watery fluid, but he thought it 
impossible to trace any difference in the ages of the various 
precipitates. His idea was that all these rocks are arranged 
in the crust as spherical or elliptical masses whose kernel is 


composed of granite, and whose outer layers comprise 
porphyry and the primitive rocks. This crude conception of 
Heim's has certain points of analogy with the much later 
theory of " central massives " promulgated by mountain 

Heim sub-divided the sedimentary or stratified deposits in 
four main groups as follows : 

4. Newer limestone, including Muschelkalk and Jurassic 

3. "Bunter" or variegated sandstone (including the sand- 
stone of Fiichsel). 

2. Older limestone or Upper Dyas ("Zechstein" of Leh- 

i. Red Underlyer or Lower Dyas ("Rothe Todtliegende " 
of Lehmann). 

He also made a special inquiry into the origin and distribu- 
tion of basalt, and wrote strongly in favour of its eruptive 
origin. He regarded it as younger than all four sub-divisions 
of the sedimentary deposits, and supposed that its eruption 
had been accompanied by violent crust-movements, during 
which the rocks were bent and fractured and the mountain- 
systems were upheaved. 

The subjects of denudation and erosion also attracted 
Heim's attention, and he gave a full description of the erosion 
of valleys by the agency of running water, enumerating many 
good examples in confirmation of his ideas ("On the Forma- 
tion of Valleys," Voigfs Magazine^ 1791). 

One of the most loyal and gifted of Werner's scholars was 
Johann Karl Freiesleben (1774-1846). He was born and 
educated at Freiberg, and enjoyed the intimate companion- 
ship of his master and patron. While attending Werner's 
classes he formed the friendship of Von Hum bold t, Von 
Buch, and Von Schlotheim; he afterwards travelled with Buch 
in Saxony, with Schlotheim in Thuringia, and with Hum- 
boldt in the Bohemian mountains, the Alps, and the Swiss 
Jura mountains. 

His first large work, 'Description of the Harz Afountains 
(2 vols., 1799), contains chiefly mineralogical and technical 
information, and a later work, Contributions to the Mineral- 
ogical Knowledge of Saxony ', published in 1817, is of the same 

As a geologist, Freiesleben accomplished memorable work 


in his study of the sedimentary series on the northern slopes 
of theThuringian Forest. His comprehensive work, Geognostic 
Contribution to the Knowledge of the Copper Slate Series, with 
special reference to a part of Mansfeld and Thuringia (Freiberg, 
1807-15, in 4 vols., and with coloured geognostic map), still 
ranks as one of the most accurate local monographs on the 
geology of North Germany. It depicts the different deposits 
according to their mineralogical character, their stratigraphical 
succession, their cartographical distribution, and the occurrences 
of fossils and minerals, in a manner so exhaustive, that later 
authors have been able to add little to his results. 

Freiesleben included under the term copper-slate or ore- 
bearing series the strata from the "Red Underlyer" to the 
" Muschelkalk" inclusive; in other words, all the sub-divisions 
now placed in the Dyassic and Triassic geological systems 
were treated by him as belonging to one great formation. 

While the Thuringian Forest and the Harz mountains 
received by far the largest share of attention from the early 
geologists, certain other parts of North Germany also found 
their way into geological literature. The neighbourhood of 
Hildesheim was made the subject of research papers by 
J. H. S. Langer in 1789, and again by J. A. Cramer in 1792. 
A paper entitled " Physical and Mineralogical Observations 
on the Mountains of Silesia," by A. Gerhard, appeared in the 
Reports of the Royal Academy of Berlin in 1771 ; and in 1795 
the mineralogist, D. L. G. Karsten, published a geognostic 
account of a journey in Silesia. Still more widely read were 
Leopold von Buch's writings on Silesian districts. His Attempt 
at a Geognostic Description of Silesia, which he dedicated to 
Professor Werner, is accompanied by a coloured general map. 
This paper, like Von Buch's earlier paper on the district of 
Landeck, is more concerned with petrographical than with 
geological details, yet it affords a good general survey of the 
geological structure of a territory previously little investi- 

An individual charm is lent to this and to all the subsequent 
works of Leopold von Buch by Kis skilful delineation of the 
relations between the geological structure and the superficial 
aspects of a country. A landscape appealed to his artistic 
sense as well as to his scientific interest, and his mastery of 
language enabled him to transfer his impressions picturesquely 
in- writing. Mineralogical descriptions were fully given; but 


from the dry details his mind would sweep with easy relief 
to the consideration of the broader truths of the science. 

The following passage may be quoted as an example of Von 
Buch's style of writing. It describes his idea of the origin of 
the Carboniferous series of rocks: "First the conglomerate 
falls, a mixture of great stones that could not be carried far 
from their parent mass, even by an angry flood; and they 
tear away with themselves the mantle of vegetation which 
had formerly reposed in security upon their surface. Woods 
are overthrown, buried beneath the irresistible rush of jagged 
and broken rock, again and again the floods rise and pour 
over the land, renewing this drama of destruction. Countless 
fragments are rolled from the heights into the narrow moun- 
tain basins and valleys ; there in the hollow they are dashed 
against one another, gyrated and rounded into pebble form. 
After the surface has been denuded of its vegetation and 
the force of the flood diminishes, the finer, lighter grains 
begin to subside and the newer fine-grained sandstone accu- 

Von Buch was particularly interested in the conglomerates, 
and on the basis of the lithological features he traced the 
pebbles and larger fragments included in the conglomerates 
very carefully to their place of origin. He demonstrated 
that the pebbles are smaller the more remote they are 
from the rock from which they have been broken, and by com- 
parative studies he tried to determine the direction that had 
been followed by the transporting floods. 

From a strictly scientific point of view, Leopold von Buch's 
geological researches were less successful than those of Voigt 
or Freiesleben, which marked a distinct note of advance in 
stratigraphical inquiry. The geological data given by Von 
Buch in his Silesian papers are sketchy in comparison, and 
there is no serious effort to draw up a definite succession of 
the rock deposits upon either stratigraphical or palseontological 

During his Norwegian journey, Leopold von Buch had 
drawn attention to the position of granite above the "transi- 
tional" limestone in the neighbourhood of Christiania. 
Soon after, in 1811, a work on the Syenite Formation in 
the Erz Mountains^ written by Raumer and' Engelhardt, 
aroused great interest. These authors stated that the 
granite and syenite on the north-east edge of the Erz 


mountains were not, as Werner had supposed, the oldest 
rocks, since they rested locally upon the gneiss and schist 
series, and even upon the strata of the "transitional" 
series. Similar observations had been made by these authors 
in the Harz mountains, and corroborative reports began to 
appear in other countries disproving the commonly accepted 
dogma that all occurrences of granite must of necessity be of 
the highest antiquity. 

In comparison with Middle and North Germany, geognostic 
research was very backward in South and West Germany, not- 
withstanding the fact that these areas are particularly rich in 
fossils, and have in later times very materially assisted in de- 
veloping our knowledge of past epochs. 

The first to examine the rocks of the Old Bavarian pro- 
vinces was Mathias von Flurl (1756-1823). At the age of 
twenty-four Flurl was elected Professor of Physics and Natural 
History in the Industrial Academy at Munich; afterwards he 
studied for a time under Werner. On his return to Bavaria, 
he was advanced from one position to another, and from 
the year 1800 occupied the post of Director of Mines. His 
chief work, A Description of the Mountains of Bavaria and the 
Upper Pfalz, was written in the form of letters. Pre-emi- 
nence was given to matters concerning mines and metallurgy; at 
the same time, he related in simple narrative style what he had 
seen of any geological interest in the course of his travels, men- 
tioned the localities where fossils occur, and noted the surface 
distribution of different kinds of rock. But Flurl avoided all 
reference to debatable points, such as the order of the succession 
of rocks, the relative age of fossils, or the mode of origin of 
the rocks. The work was accompanied by a small general map 
of Bavaria, wherein a few of the leading varieties of rock were 
distinguished granite, gneiss, schist, limestone, sandstone, 
nagelflue, and alluvium. 

Flurl was thus the pioneer of geology in Old Bavaria, and 
his work has a permanent value on account of its reliable and 
varied information. On the other hand, it cannot be placed 
on the same scientific platform as the more special contribu- 
tions to geology made by his contemporaries in Northern 

B. Austria- Hungary and the Alps. A foundation had been 
constructed for the geological investigation of Austria-Hungary 


by Ferber's important series of works, bis Treatise on the 
Mountains of Hungary, his Account of Travels, and his Con- 
tributions to the Mineralogy of Bohemia (Berlin, T 774). Twenty 
years later, another descriptive work on the minerals of Bohemia 
was contributed by Franz Ambros Reuss, a mineralogist and 
physician resident in Bilin. The same author wrote a Text- 
book of Mineralogy that had a wide circulation. A pupil of 
Werner's, Reuss treated the basalts of North Bohemia as rocks 
of aqueous origin. 

The most gifted of the early stratigraphers was Johann Ehren- 
reich von Fichtel (1732-95), a Hungarian by birth, whose 
researches in Transylvania were published in 1780; a later 
work on the Carpathian mountains appeared in 1791. The 
first volume of Fichtel's Mineralogy of Transylvania contains 
much valuable information about local occurrences of Tertiary 
fossils in the low range of hills in front of the Transylvanian 
Alps. In the second volume, Fichtel describes the massive 
accumulations of rock-salt in Transylvania, and gives an 
exhaustive technical account of the whole mining industry in 
Transylvania, the Carpathians, and Galicia. A topographical 
map shows the distribution of rock-salt in these areas. 

Local stratigraphical relations are now and then elucidated, 
and the origin of the different kinds of rock is discussed, Fichtel 
declaring himself to be a thorough Volcanist. Amongst rocks 
of igneous origin Fichtel includes the granite composing the 
highest mountains, and the gneiss, schist, limestone, and 
metalliferous rock (rhyolite, dacite, trachyte) composing the 
mountains of intermediate height; the rocks composing the 
lower ranges in front of the middle and main chain are, he says, 
of pelagic origin, and include sand, clay, and pebble deposits. 
According to Fichtel, rock-salt originated by the evaporation 
of a fluid mixture of salt and rock-oil, which had sapped into 
huge crust-cavities after the cooling and consolidation of the 
earth's crust. Such cavities, with their saline intercalations, 
form, he says, the heart of the Carpathian mountains. 

Fichtel's later work is devoted chiefly to a careful enumera- 
tion and description of the eruptive rocks in the Carpathians. 
He distinguishes volcanic outbreaks, with which superficial lava 
flows are associated, from volcanic upheavals, in the course of 
which wide regions are affected, and masses of igneous material 
are intruded in the crust. 

It can be easily understood that Fichtel's v/ork met with an 


incredulous reception by Werner and his adherents. One of 
those, Jens Esmarch, afterwards Professor of Geology in the 
University of Christiania, travelled through the districts which 
Fichtel had described. In all the localities where Fichtel had 
found evidence of the igneous as opposed to the aqueous origin 
of the primitive rocks, Esmarch could see only a confirmation 
of Werner's teaching (Short Description of a Journey through 
Hungary^ Transylvania^ and the Banat Mountains, Freiberg, 


The writings of the energetic but somewhat eccentric 
traveller Hacquet J in many respects supplemented the works 
of Fichtel. 

Racquet's records of his journeys in the Carpathian and 
Transylvanian mountains were, however, written towards the 
close of his active life. His fame is based upon another work, 
the Oryctograpkia Carniolica, a study of the surface conforma- 
tion of Carniola, Istria, and neighbouring districts (4 vols., 
Leipzig, 1778-89). This monograph, which was modelled 
after the pattern of the Swiss geologists, Scheuchzer and De 
Saussure, represented the fruit of twenty years' residence in 
Carniola, and disclosed for the first time something of the 
mineralogical and physical structure of the more remote 
southern ranges of the Alps. A geographical map was 
published along with the work. 

The scenic character and physical relations of the country, 
as well as the customs and character of the population, are 
excellently depicted. But in the geological portion the author 
unfortunately confined himself to a barren description of the 
individual occurrences of rocks, minerals, and fossils, without 
attempting to give a general conception of the structure. 
During the years 1781-86, Hacquet extended his knowledge of 
the Alps by travelling through the Dinaric, Julie, Rhsetic, and 
Noric Alps. He then published a work of a more mineral- 
ogical and geological character upon these districts, but he did. 
not succeed in arriving at any real appreciation of the broad 
features of Alpine structure. 

This was a task even beyond the greater powers of Leopold 

1 Balthazar Hacquet (1739-1815) had a varied career. Born in Brittany, 
he became a surgeon ; in that capacity he attached himself to the Austrian 
Army throughout the Seven Years' War. At the close of the war he taught 
Surgery at the Lyceum of Laibach, and in 1788 he was made Professor of 
Natural History and Surgery in the University of Lemberg. 


von Buch and Alexander von Humboldt. During the winter 
spent by the two friends in Salzburg, they made numerous tours 
into the Salzkammergut and Gosau Valley. Von Buch's 
account of the geognostic and physical relations in that locality 
is very pleasant reading; but, biassed as he was by Werner's 
theories, Von Buch tried to explain the disturbances of the 
strata by local collapse, and by the shifting of the centre of 
gravity in the rocks. The beautiful " Konigsee " near Berchtes- 
gaden, and the Lake of Hallstadt, were both regarded as 
local basins of inthrow, and the deep Alpine valleys were 
attributed to river erosion. The whole massive development 
of limestone in the higher ranges of the Salzkammergut was 
taken to be the equivalent in age of the Thuringian " Zech- 
stein " (Upper Dyas). The occurrence of fossils at Hallstadt 
and Gosau, and other now famous localities, was repeatedly 
mentioned by Von Buch, but the fossils themselves were 
not used in any way to help to determine the age of the 

In a separate publication Von Buch drew a comparison 
between the geological succession observed by himself across 
the Brenner Pass, and that which had been described by De 
Saussure for the Mount Cenis Pass. Although the idea was 
good, the rocks and the stratigraphy in these two distant 
Passes have too little in common to disclose any broad 
principles of Alpine structure, and the results obtained by Von 
Buch in this respect were confused and unsatisfactory. 

Some general facts were, however, brought into promi- 
nence. In this work Von Buch demonstrated the absence of 
porphyry at Mount Cenis, as well as in the whole Northern 
Alps, in strong contrast to the enormous development of this 
rock south of the Brenner Pass; he compared the northern 
and southern zones of the Alps with one another geologically; 
showed the relationship of the Jura mountains, to the Alps and 
he drew attention to the lithological differences in the rocks, 
and their influence on the scenic features. In later years Von 
Buch wrote a few short papers on the Hinterrhein district 
(1809) and on the Bernina Massive (1814). 

One of the most richly endowed of Alpine students was the 
Ziirich geologist, Hans Conrad Escher (1767-1823). In 1796 
Escher published a geological survey of the Swiss Alps, and 
afterwards a series of geological sections from Ziirich to the 
St. Gothard Pass. He also contributed several smaller 


papers to Leonhard's Taschenbuch fur J\fi/teralogie and other 

Escher's modest personality is endeared in the minds of all 
Alpine geologists. His quiet, persistent spirit of inquiry 
enabled him to amass innumerable observations, which not 
only afforded a reliable framework for the future, but also 
contained the kernel of some of the grandest mental concep- 
tions of geological phenomena that have been attained during 
the progress of Swiss geology. 

While Escher's work is so empirical and technical in its 
tendency as to have retained its freshness for the specialist, his 
contemporary, J. G. Ebel, 1 has left a work whose chief 
interest now is for the historian, but which, nevertheless, was a 
great achievement at the time. Ebel was the first to bring any 
comprehensive account of Alpine geology to a relatively 
successful fulfilment. The previous literature of Swiss geology, 
from which Ebel drew his facts, embraced the works of 
Scheuchzer and De Saussure, the series of accurate geological 
sections prepared by the engineer of the Linth Canal, Hans 
Conrad Escher, and the papers of the younger Escher, which 
were then appearing in current magazines. De Luc and De 
Saussure had contributed a few observations on the south- 
west portion of the Swiss Jura mountains, and Count Razu- 
mowsky had published his large work, Natural History of the 
Jorat and its Surroundings, in the second volume of which 
important suggestions had been given regarding the structure 
of the Jura mountains. Ebel was also thoroughly familiar with 
the geological literature of the German, Austrian, French, and 
Italian Alps; in many cases he relied upon his own obser- 
vations. . 

Ebel's description of the Alps was characterised by the 

1 John Gottfried Ebel, born 1764 in Ztillichau. Silesia, studied medicine, 
then travelled three years in Switzerland, and in 1793 settled as a physician 
at Frankfort-on-Main. A translation of the writings of Sieyes brought him 
under political suspicion, and he was forced to leave Germany. He went 
to Paris, where he continued to practise medicine, but spent a large portion 
of his time in the pursuit of natural philosophy. In 1810 he selected Ziirich 
for a residence, and died there in 1830. During his early years in Frank- 
fort he published a " Guide," How to Travel in Switzerland in the most 
Pleasant and Practical Way (4 parts, 1793), a work which has served as the 
pattern of our present guide-books for travellers. His next work was A 
Description of the Mountain-peoples of Switzerland, 1798-1802. His chief 
geological work, On the Structure of the Earth in the Alpine Mountain' 
System, was published at Zurich in 1808. 


clearness with which he distinguished the leading members of 
the mountain-system. He established the fundamental dis- 
tinction of a central chain composed for the most part of 
primitive rocks, and two lateral zones on the north and on the 
south of the central chain, composed chiefly of limestone, 
sandstone, shale, and nagelflue. These leading zones were 
accurately described with respect to their geographical distri- 
bution and the various kinds of rock present in them. The re- 
semblances and differences between the northern and southern 
zones were pointed out, and the leading stratigraphical features 
were shown in a number of geological sections. The text was 
further illustrated by a general geological map of the Alps and 
several panoramic sketches. A geological map (on small 
scale) of the mountain-systems of Europe was added for 
purposes of comparison. 

In describing the Jura mountains, Ebel defined their geo- 
graphical limits in accordance with their geological structure. 
He pointed out for the first time that the Swabian and 
Franconian Alb formed geologically an integral part of the 
Swiss Jura chain. He also drew special attention to the 
arched forms of structure as particularly characteristic of the 
Jura mountains, but failed to find any satisfactory explanation 
of the curvature of rock-strata. 

The main features of the conformation were thus rightly 
laid down, but the detailed stratigraphy was less ably handled. 
Ebel started from the assumption that the whole outer crust 
of the earth is everywhere composed of the primitive rocks, 
granite, gneiss, and crystalline schist, and that these rocks have 
been in certain localities covered by pelagic or terrigenous 
deposits. He regarded the highly-tilted position of the rocks 
in the central chain as essentially characteristic of the primitive 
series, and accepted Alexander von Humboldt's doctrine that 
the primitive rocks everywhere strike in the same direction, 
from south-west to north-east. 

In his treatment of the stratigraphical succession in the 
lateral Alpine zones Ebel attached little weight to the order of 
rock-formations enunciated by Werner, and considered it far 
more important to note the sequence of the fossil contents. 
He pointed out that the strata reposing upon the primitive 
group contain a few pelagic fossils; in younger strata the 
remains of marine faunas are much more numerous and varied; 
in still younger terrigenous deposits there are fossil fishes and 


plants; then amphibians appear, and finally, whole skeletons 
of terrestrial mammals and birds are imbedded in the sands 
and clays. "Accordingly fragmentary historical testimony of 
the beginnings and further stages of living organisms on the 
face of the earth has been indelibly preserved in the suc- 
cessive strata. It must be left to posterity, by means of 
the united observations and efforts of many enquirers, to 
solve the secrets of the earth's structure and read aright the 
sequence of organic remains interred in the crust " (vol. ii., 
p. 412). 

The periodicity in the recurrence of certain physical con- 
ditions and the repetition of similar deposits were favourite 
themes with Ebel. He showed that the same varieties of rock 
occur repeatedly in the lateral zones of the Alps, and clearly 
represent deposits gathered during different geological epochs. 
Then he cited evidences, both from the central and lateral 
Alpine zones, of recurrent paroxysms of the crust; these, in his 
opinion, had been caused by the sudden transgression of the 
ocean over terrestrial areas and the consequent devastation of 
the land, erosion of valleys, and accumulation of fine and 
coarse mechanical deposits at the base of the mountains. 

According to Ebel, the last and most violent inundations 
had advanced in a direction from south-west to north-east, and 
had transported the huge erratic blocks and the material of the 
nagelflue and other pebble deposits to the northern band of 
the Alps, and even as far as the North German plain. 

This same idea of periodicity led Ebel further astray when 
he ventured into philosophical speculations. He compared 
the body of the earth with a voltaic pile in spherical form, in 
which a living element analogous with the electrical current 
not only called forth the plant and animal kingdoms, but also 
regulated the origin and arrangement of the minerals and 

Such theoretical speculations were always kept apart from 
the descriptive portion of Ebel's work, and scarcely affected 
it, although they produced so unfavourable an impression 
that they caused his work to be undervalued by his con- 
temporaries. At the same time, Ebel's work undoubtedly 
marks the high level of geological research as it was repre- 
sented in the Alpine literature at the beginning of the century. 
Unfortunately, Ebel had no deep insight into stratigraphical 
details, and he lacked the genius to follow up the indications 


which De Saussure and Escher von der Linth had given of the 
grand crust movements that had inverted rock -strata and 
developed the fan-structure of the mountain-massives of the 
central chain. The bolder thoughts of these men escaped 

In addition to the larger works on Alpine geology by 
Von Buch and Ebel, a number of smaller treatises on Alpine 
localities were contributed to mineralogical journals. Amongst 
these were papers by Italian geologists directing attention to 
the interesting geological phenomena in the Fassa Valley and 
Predazzo in South Tyrol ; a description by Mohs of the Villach 
Alps ; works by Charpentier and others on the Wallis Alps; and 
by several French geologists on the Maritime Alps and several 
parts of the Dauphind 

C. Italy. The interest of Italian geologists was early 
attracted to the richly fossiliferous Tertiary strata. Arduino's 
epoch-making works on the stratigraphical succession in the 
neighbourhood of Verona have been mentioned above (p. 37). 
The travelled Alberto Fortis (1741-1803), an Augustine monk, 
was an acute observer and a prolific writer on geological 
subjects. His works are for the most part descriptive of the 
Tertiary deposits and volcanic rocks in the Vicentine Alps ; 
Monte Bolca, a locality long famous for its fossils, was 
thoroughly searched by Fortis, and he discovered several new 
localities of well-preserved fossils (Brendola, San Vito, Gran- 

Fortis compared the fossil fishes of Monte Bolca with exist- 
ing species in the southern seas, and concluded that six or 
seven species were identical. This opinion was shared by 
Volta, in whose splendid monograph of the Monte Bolca 
fishes (1788) the number of fossil forms identical with living 
species is increased to one hundred and ten. Possibly the 
best contribution made to science by Fortis was his work 
on the geological structure of Dalmatia, and his account of 
the occurrence of nummulites at Bencovac and Sebenico, of 
bone breccias at Cherso, etc. 

In regard to the origin of basalt and tuffs, Fortis was an 
extreme Volcanist ; he even believed that the volcanic energy 
of the Vicentine area had raised the temperature of the Adri- 
atic Sea to such a degree that tropical molluscs and fishes 
could then exist in it. 


The Tertiary fossils of Italy were made the subject of a 
masterpiece in pala^ontological literature, Brocchi's l famous 
monograph, Conchylioloia fossile subapen nina (Milan, 1814). 
This work comprises two quarto volumes, and is handsomely 
illustrated with sixteen plates. It begins with a historical 
review of the development of palaeontology in Italy, depicts 
in an introductory chapter the structure of the Apennines and 
the adjoining plains, and distinguishes the Secondary rocks 
which compose the true mountain-chain from the Tertiary 
deposits on the lower slopes and plains. The main part of 
the work is occupied by the specific descriptions of Tertiary 
mollusca from all parts of Italy. The special locality, the 
number of specimens, and the particular distribution in sandy 
or clayey, pelagic, or littoral deposits is accurately recorded 
for each species; both the descriptions and illustrations are 
perfect. A special chapter is devoted to the occurrence of 
land mammals, whales, and fishes. 

Brocchi recognises the great similarity of the Tertiary species 
of mollusca with species still living in the Mediterranean and 
Adriatic seas, and likewise the difference between the Italian 
fossil species and the species of the Paris basin, which had 
been described by Lamarck and Brongniart. He erroneously 
attributed the dissimilarity of the Italian and French species, 
not to any difference in the geologic age, but to the separa- 
tion of the areas of occurrence. At the same time Brocchi 
fully realised the fundamental difference between the fossil 
faunas in the Secondary and Tertiary rocks of his native 
land. The numerous occurrence of Belemnites, Ammonites, 
Terebratulas, and other generic types in the Secondary rocks, 
and their complete absence from the Tertiary faunas is ex- 
plained on the basis of the gradual extinction of the more 
ancient types during the vast periods of time that elapsed 
while successive strata accumulated. 

Brocchi's ideas about the mode of extinction and period of 
existence of fossil genera and species are of especial interest. 

1 Giovanni Battista Brocchi (born at Bassano in 1772) studied juris- 
prudence and theology in Padua, was made Professor of Natural History 
in Brescia, and afterwards Inspector of Mines for the Kingdom of Italy. 
He travelled through almost the whole of Italy, and published a large 
number of mineralogical, geological, and paloeontological papers; in 1823 
he travelled in the East, visited Lebanon and Egypt, and went as an 
engineer to the Soudan, where he died in 1826 at Khartoum, a victim to 
the unhealthy climate, 


He opposes the Catastrophal Theory, which taught that from 
time to time destructive catastrophes had occurred in past 
ages, and had annihilated the whole or the greater portion of 
existing forms ; and he lays down principles of the evolution 
of one from another along continuous lines of descent, but 
in accordance with definite natural laws of growth and decay. 
He argues that just as a definite span of life is meted out to 
each individual, and the time may be longer or shorter accord- 
ing to the kind of organisation, in the same way each species 
and each genus possesses a definite energy of existence, and 
when that has been exhausted, death ensues from natural 
causes of decay. 

While it is as a palaeontologist that Brocchi's name will be 
remembered, his first contribution was a mineralogical and 
chemical treatise on the iron-works of Mella, in Val Trompia; 
he then studied the porphyrites and basalts of the Fassa valley, 
and, in agreement with Wernerian doctrines, referred them to 
an aqueous origin. Later in life, after the publication of his 
monograph, he returned to the study of volcanic rocks, with 
the result that he became a Volcanist. 

The volcanoes of South Italy had always proved an attractive 
study in scientific circles, and yet it was remarkable how few 
of the scientific works regarding them had been contributed 
by those resident in the immediate neighbourhood. 

Sir William Hamilton's work on Vesuvius and Etna (p. 45) 
had prepared an excellent foundation for further research, and 
a worthy continuation was provided by the Frenchman, Dolo- 
mieu, 1 in his descriptions of the Lipari and Pontine Isles, and 
his detailed mineralogical researches on the rocks of these 
islands and of Etna. 

Dolomieu departed from the usual method of research that 

1 Guy S. Tancrede cle Dolomieu, born 175 a t Dolomieu, in the 
Dauphine, was an officer in the army; he travelled for several years in 
Sicily, South and Central Italy, the Pyrenees and Alps; in 1796 he was 
elected a Professor in the Paris School of Mines, and accompanied the 
French Expedition to Egypt. While on the return journey he was taken 
into custody, for political reasons, in Naples, and was imprisoned for two 
years. After he regained his liberty he became, in 1800, Professor of 
Mineralogy at the Natural History Museum in Paris, but died in the 
following year in Paris. His most important works are: Ti'aveis in 
the Lipari Isles (Paris, 1783); On the Earth-Tremors in Calabria (Rome, 
1784) ; On the T^pontine Isles ^ and a Catalogue of the Products of Etna 
(Paris, 1788). 


had been adopted by his predecessors. Instead of confining 
himself to a description of the superficial aspect of the volcanic 
mountains and the characteristic phenomena of eruption, Dolo- 
mieu studied the lavas, loose ejecta, sublimations, etc., and 
compared these volcanic products with other rocks. He thus 
arrived at the result that all transitional stages exist between 
the coarsely crystalline lavas and the glassy rocks (obsidian, 
pitchstone), the latter being merely particular structural varieties 
of the crystalline lavas. 

In order to explain the possibility of so many grades of 
structure, Dolomieu supposed that volcanic heat, unlike any 
kind of artificial heat that could be produced in the laboratory, 
did not reduce the original rock-material to a completely melted 
mass, but merely to a viscous state, in which the individual 
mineral constituents could move relatively to one another 
while still retaining their characteristic form. 

He further supposed the lavas contained a combustible sub- 
stance (perhaps sulphur), which held the rock in this viscous 
state until it was completely consumed ; and that this com- 
bustible substance, by its expansive force, produced the 
scoriaceous, slaggy, and irregular surfaces of lava streams, 
and caused the upward pressure of molten magma to the 
orifice of escape. 

Dolomieu confirmed the igneous origin of basalt rock, re- 
garding it as a variety of lava for the most part associated with 
submarine eruptions. He compared the alternating lava streams 
and sedimentary strata at Etna with the stratigraphical relations 
of the so-called trap-rocks in the Vicentine district, and con- 
cluded that the latter gave evidence of volcanic activity. 

The name of Dolomieu is perpetuated in the name of the 
" Dolomites," given to the beautiful district in South Tyrol 
south of the Puster Valley. Dolomieu called attention in 1791 
to the unusual mineralogical character of the " Alpine lime- 
stone" in that district. His chemical investigations proved the 
rock to contain, in addition to lime carbonate, a very high per- 
centage of magnesium carbonate ; so that the rock could by no 
means be regarded as a true limestone. Afterwards, any highly 
magnesic limestone came to be called "Dolomite" rock. 

In 1797 Dolomieu confirmed the statement of Giraud 
Soulavie, that the volcanoes of Auvergne and Vivarais are 
intruded into the granite, and partially rest upon it. Thus 
Dolomieu extended our knowledge of the mineralogical com- 



position of rocks on many definite points, and his researches 
at once gained recognition. Italian geologists applied them- 
selves with fresh zeal to the study of their volcanic rocks, 
working more by the practical methods of Dolomieu. Soon 
they discovered the weaknesses in Dolomieu's writings, where 
that keen observer had ventured to speculate on the causes 
which might determine the particular setting and orientation 
of mineral material characteristic of the transitional varieties of 
igneous rocks. 

The learned Lazzaro Spallanzani (1729-99), Professor of 
Natural History in Pavia, was the first who applied experi- 
mental methods to the elucidation of volcanic rock-structure. 
He set up series of experiments in his laboratory in order to 
find out whether gaseous vapour would escape when lava was 
melted, and what was the chemical nature of such vapours. 
The result showed that little gas escaped, but the powdered 
lava partially sublimated, and was partially converted into a 
vesicular rock-mass. 

Spallanzani then tested Dolomieu's idea that the crystalline 
structure of volcanic rocks was produced under the influence of 
a moderate degree of volcanic heat acting during a long period. 
Different kinds of lava were exposed to definite tempera- 
tures for forty-five days, some even for ninety days. The 
result of Spallanzani's experiment appeared negative, since a 
moderate heat acting for a long time produced precisely the 
same effects as a more intense heat acting for a shorter period. 

Spallanzani also investigated whether, in accordance with 
the hypothesis of Dolomieu, the presence of sulphur would 
hasten the fluidity of the lava, and whether the melted material 
in this case would solidify as a crystalline, rough-grained, or 
vitreous rock. The result was again negative. The powdered 
specimens of lava mixed with sulphur demanded the same time 
to become fluid as the specimens with which no sulphur had 
been mixed, and on solidifying produced the same glassy rock. 
Spallanzani therefore opposed Dolomieu's theory, that a com- 
bustible substance was present in flowing lava, pointing out 
(i) that no flames had ever been seen on the surfaces of lava 
streams; (2) that all lavas were easily brought back to a fluid 
condition ; whereas if Dolomieu were right in supposing they 
became solid after all the combustible material had been con- 
sumed, then in the absence of the latter it should be much 
more difficult to melt the lavas. 


Spallanzani's experimental researches were published in 
several volumes in the same series as the more popular descrip- 
tive account of his travels (Travels in Sicily and some parts 
of the Apennines, 6 vols., Pavia, 1792-97). His descriptions 
and observations of volcanic regions surpass in scientific 
accuracy and completeness all previous contributions of the 
kind, and have secured a permanent place in the literature 
of scientific travel. Although Spallanzani's numerous experi- 
ments invariably produced vitreous rock-varieties, Hall suc- 
ceeded shortly after in demonstrating that crystalline structure 
could be produced experimentally by the slow cooling of melted 

In 1801, Scipio Breislak (p. 78) published a descriptive and 
geological work on the Phlegrsean fields, the extinct volcanoes 
near Rocca Monfino, on Monte Somma, Vesuvius, the Baise, 
Procida, and Ischia. This work comprises several maps, and 
is in many respects supplementary to Spallanzani's Travels. 
Breislak also contributed the first researches on the geology 
and stratigraphy of Rome, and of that part of the Apennines 
which surrounds the volcanic area of the Italian mainland. 

Leopold von Buch was also a contributor to the geology 
of Rome. His study of the basalt of Capo di Bove and the 
Alban mountains aroused in his mind the first doubts of the 
correctness of Werner's Neptunian doctrine. The best feature 
in Von Buch's summary of the geology of Rome is his lucid 
exposition of the travertine and tuff deposits. He demonstrates 
that these are true aqueous sediments, although he recognises 
the volcanic origin of many of the contained mineral fragments. 

In a paper "On the Formation of Leucite," Von Buch tried 
to prove that the crystals of leucite in the lava had separated 
out while the material was still in a fluid state. In his estima- 
tion the leucite crystals were original volcanic products; he 
discredited the hypothesis that they had been originally 
components of an aqueous sediment which had been 
partially melted in subterranean volcanic cisterns and poured 
forth as lavas. The anti-Neptunian attitude assumed by 
Von Buch in this paper was turned to good account at the 
time by the Volcanists. But Von Buch still held a somewhat 
contradictory position regarding basalt. 

After he had visited Vesuvius and the Euganean Isles, in 
1799, he wrote to Pictet that little -difference could be 
distinguished between the lava flow from Torre del Greco 


and basalt rock; but as Hall's experiments had shown that 
basalt when melted could again solidify in crystalline form, he 
supposed that the lavas of Vesuvius represented a pre-existing 
basalt of aqueous origin which had been melted in the 
earth's crust and ejected as lava. In other cases, for example 
at Solfatara, the lava might not be basaltic in character, and 
might have some other origin- In the same letter he gave a 
description of the definite sequence in the eruptive phenomena 
of Vesuvius. The eruptions, he said, begin with earthquakes, 
radial fissures form on the slopes of the mountains, and lava 
wells out; then the pent-up steam and vapours burst forth 
from the central vent with explosive force and noise, throwing 
into the air enormous masses of ashes and fragmentary scoriae 
amidst dust and smoke. After the crater is emptied, quiet is 
regained, the exhalations of injurious gases marking the final 
stages of a spent volcanic outburst. 

While our scientific knowledge of volcanoes was derived in 
great measure from Italy, that country also was the scene of the 
series of earthquake shocks which convulsed Calabria in 1783. 
Great importance is attributed to the Calabrian earthquake 
in scientific literature, from the circumstance that many of 
the observers present in Calabria during the disturbance, or 
immediately after it, were experienced men of science, and 
their vivid descriptions and accurate observations and drawings 
afforded the first circumstantial scientific account of earthquake 

D. France, Belgium, Holland, and the Iberian Peninsula. 
During the eighteenth century France had fallen behind 
Great Britain, Germany, and Italy in the pursuit of geology 
and palaeontology, but the influence of Buffon revived a 
warmer interest in these studies. Scarcely any other country 
in Europe offers such a fine field for geological studies as 
France. Apart from the Pyrenees, Alps, Brittany, and the 
Ardennes, the stratigraphy of French districts is comparatively 
simple, and the strata abound with a wealth of well-preserved 
fossil remains. In addition, there is the wonderful Auvergne 
district, with its groups of extinct volcanoes, discovered by 
Guettard in 1752. 

Desmarest was the French geologist whose genius disclosed 
the full significance of these extinct volcanoes and made 
Auvergne famous. In 1763 he observed on the plateau of 


Prudelle, near Clermont, basaltic pillars in close relationship 
with a lava flow, and he spent many years in collecting facts 
to prove the volcanic origin of the basalt. The work which 
he published in the Memoires de r Academic royale des Sciences 
(1774-75) established the igneous origin of basalt without a 
shadow of doubt. 

Desmarest was himself so entirely convinced of the result 
of his conclusions that he took no part in the strife between 
Neptunists and Volcanists, but when questioned by .any .hesi- 
tating adherents of either party he usec io , reply laconically, 
"Go and see." 

It was remarkable how complete 1 )'. Werner, and, h]? school 
ignored the incontestable results Of Desmarest. And the 
later work by Desmarest, " On the Determination of different 
Epochs of Volcanic Activity in Auvergne," was also neglected 
in Germany (Mem. de rinst. Sc., Math, et Phys., 1806). His 
own countrymen, however, fully realised the value of Desmarest's 
achievements. Following the same lines as Desmarest, Faujas 
de Saint-Fond and Abbe Soulavie made known the volcanoes 
of Vivarais and Velay with their magnificent basaltic pillars and 
lava streams ; so that when D'Aubisson, a student of Werner's, 
returning to Paris from Freiberg, tried to spread Neptunian 
doctrines, he had no success, and a visit to Auvergne con- 
verted D'Aubisson himself to Volcanistic beliefs. 

The intellectual politician and scientific investigator, Count 
Reynaud de Montlosier, published in 1789 an Essay on the 
Volcanoes of Auvergne, in which he promulgated a new theory 
about volcanoes. Like Desmarest, Montlosier recognised that 
there were in Auvergne volcanoes of different ages. The 
younger have preserved their typical conical form and their 
craters uninjured. The older are for the most part situated 
at higher levels, and these characteristic features are absent ; 
they are connected ridges or isolated mountains composed of 
pillared basalt, or trachytic rocks, frequently reposing on 
granite. Whereas it is clear that the younger craters and 
cones of loose ejected material and lava are of true volcanic 
character, Montlosier claimed for the older and relatively 
higher groups of igneous rocks that they represented a single 
upheaval of an extensive viscous mass of rock-material that 
had then cooled in the elevated position. 

The Pyrenees also attracted the attention of French geolo- 
gists towards the close of the eighteenth century. Abbe 


Palassou wrote the first full scientific description of the geolo- 
gical structure of the Pyrenees. He worked nearly forty 
years in this district, and in 1782 published his Essay on the 
Mineralogy of the Pyrenees Mountains. The work comprises 
eight mineralogical maps on a large scale, and twelve plates 
with panoramic views. After the precedent of Guettard, Palas- 
sou used special symbols to distinguish the different rocks 
and minerals on the maps; and took careful observations 
of the. strike and dip. Palassou concluded that the whole 
mountain-chain .is made, up of limestone, shales, clay, and 
granite, with a general strike in W.N.W. and E.S.E. direc- 
tion, an.d he gave. a number of transverse sections displaying 
a simple and uniform structure throughout the chain. 

Palassou's work was based upon principles which were 
already somewhat antiquated when the work appeared. He 
believed that the sedimentary rocks had been deposited in the 
various inclined and horizontal positions in which he found 
them. Limestones and fossiliferous shapes of all ages were 
termed Secondary formations; no attempt was made by 
Palassou to determine systematic sub-divisions according 
to the rock varieties, the fossils, or any other individual 
feature, and he discarded the "transitional" series of forma- 
tions between the primitive granitic rocks and the Secondary 

Among the varieties of rock a diabasic rock containing 
uralite was described for the first time under the name of 

An engineer, Picot de Lapeirouse, published a finely illus- 
trated work on the Rudistes or Hippuritidse, a fossil Lamelli- 
branch family represented in great numbers of individuals in 
the Cretaceous deposits of the Pyrenees. This remarkable 
genus had been discovered by Abbe Sauvage in the Cevennes 
mountains forty years previously. Unfortunately Lapeirouse, 
beautiful as his illustrations are, entirely misjudged the place 
of these fossils in the animal world, and called his work A 
Description of several new kinds of Orthoceratites Ostradtes 
(Erlangen, 1781). 

Ramond de Carbonnieres contributed several geological and 
palseontological works on the Pyrenees. He was an enthusi- 
astic mountaineer and made a special examination of Mont 
Perdu, which was then thought to be the highest summit of 
the chain. He proved that this summit was not composed of 


granite as had been supposed, but of " Secondary " limestone 
containing numerous marine fossils. Ramond also drew atten- 
tion to the presence of horizontal and inclined strata, and to 
the fan-shaped form in which the inclined strata were often 

Johann von Charpentier (1786-1855), the son of Wilhelm 
von Charpentier (p. 38), travelled as a young man for 
four seasons in the Pyrenees (1808-12). The geological 
work which he published in 1823 was for a long time the 
standard work upon these mountains. The younger Charpen- 
tier agreed with Palassou and Ramond regarding the parallel 
trend of the strata along a definite strike, and demonstrated 
that the sedimentary strata slope away from the granite core of 
the chain. He established for the first time that there was 
a transverse fault through the whole breadth of the chain 
between Montrejeau and Perpignan, the eastern part of the 
chain having been displaced to the north relatively to the 
western portion. 

As a student and follower of Werner, Charpentier, like 
Palassou, supposed that the aqueous deposits had consoli- 
dated in their inclined position, and. gave no credence to ideas 
of subsequent uplift and disturbance. He distinguished eight 
formations, in ascending order granite, mica schist, primitive 
limestone, transitional limestone, red sandstone, Alpine lime- 
stone, and Jura limestone, ophite and terrigenous deposits 
(Tertiary and Diluvium). Charpentier gave little attention to 
the fossils, therefore not infrequently made blunders with 
respect to the age of the stratigraphical deposits. For ex- 
ample, Charpentier's "primitive" limestone corresponds to 
Silurian and Devonian formations; his "transitional" lime- 
stone, containing belemnites and ammonites, corresponds to 
the Jurassic formation; his "Alpine" limestone to Cretaceous 
and Lower Tertiary rocks. In spite of these shortcomings, 
Charpentier's work was one of the most important of his time. 

Occasional observations had been made on the "Paris 
Basin of Deposits" by Guettard, Desmarest, and others; 
Lamanon gave special attention to the beds of gypsum near 
Paris, and rightly regarded them as the deposits of a fresh- 
water lake. De la Metherie had attributed them to volcanic 
origin. Lamanon, however, found fossil specimens of a fresh- 
water mollusc in the interstratified marls, and in the gypsum 
bones of terrestrial mammals different from those of living 


species. The great chemist Lavoisier made several geological 
sections through the Paris basin, and pointed out the alterna- 
tion of littoral and pelagic deposits. The stratigraphical 
succession established by Lavoisier was added to by Coupe's 
detailed examination of exposures in the vicinity of Paris. 

The greatest work on the " Paris Basin" appeared in 1808, 
in the Journal des Mines and Annales du Museum. The authors 
were Brongniart, Professor of Mineralogy in the Natural 
History Museum in Pans, and Cuvier, the famous zoo- 
logist and palaeontologist. They drew up a systematic table 
of the succession of stratigraphical horizons in accordance 
primarily with the sequence of the deposits in the ground, 
and with the particular fossils characterising each group of 
deposits ; the varieties of rock, and the thicknesses and dis- 
tribution of different deposits were also fully considered. The 
following are the formations, in ascending order from the 
Cretaceous rocks, as they were recognised in the first work by 
Brongniart and Cuvier : 

9. Loess clay and pebble deposits, containing bones of large 
terrestrial mammals. 

1. Unfossiliferous millstone quartz and fresh- 
water limestone of Beauce (Orleans), con- 
taining species of Planorbis, Cyclostoma, 
Helix, and terrestrial plant-remains. 
Sandstone, without molluscan remains (Fon- 
Now rank tainebleau sandstone). 

as 6. Siliceous limestone, a facies of deposits 5 

Oligocene and 7 present in the southern parts of the 

deposits. basin. 

;. Sands and sandstone with molluscan re- 
mains (Fontainebleau sandstone). 
.. Gypsum and fresh- water marls, etc., with 
Planorbis, Linnaeus, etc., passing upward 
into marine oyster beds. 

Sands and coarse limestone series of Paris. 

2. Plastic clay without fossils. 

Now rank 


i. Cretaceous rocks ; fifty fossil species were enumerated in 

the chalk deposits. 

A second and larger work was issued by the same authors 
in 1811, with a special part devoted to geological descriptions, 


maps, and sections. The stratigraphical succession was 
slightly changed ; eleven sub-divisions were recognised instead 
of nine, the millstone quartz in No. 8, and the marine oyster 
beds in No 4, being erected into independent sub-divisions. 

Upon the basis of their measurements of the thickness of 
individual deposits, Brongniart and Cuvier were able to arrive 
at definite conclusions regarding the configuration of the chalk 
surface before the deposition of the plastic clay. They demon- 
strated that the clay had been deposited upon an irregular^ 
surface of pre-Tertiary hills and valleys, and that, owing to the 
inequalities of the base of deposit, neither the clay nor the 
succeeding coarse limestone series extended over the whole 
area as connected layers. After the deposition of the coarse 
limestone, the sea withdrew, and the Paris area then became 
a fresh-water basin in which calcareous, gypsiferous, argil- 
laceous and marly sediments successively accumulated. The 
gypsiferous strata were thickest in the middle of the basin, but 
neither they nor the fresh-water sediments were smooth layers. 
It was only when the sea once more had ingress and brought 
into the basin immense quantities of sand that an even surface 
of deposit was attained. Again the sea retreated, and the area 
became one of marshes and lakes in which the younger cal- 
careous and siliceous deposits gathered; as the area continued 
to emerge the surface was eroded, and valley depressions and 
uplands took shape which were quite independent of the pre- 
Tertiary configuration. 

The importance of this work for geology will be realised 
when it is remembered that with the exception of formations 
i and 9, all other formations in Brongniart and Cuvier's Table 
were unknown in Werner's system of the rock-succession 
(p. 58). Afterwards it was demonstrated that many of the 
fossils of the Paris basin agreed with the fossils in the deposits 
near Verona which Arduino had termed Tertiary deposits. And 
the series was then incorporated in the chronological succession 
of the rocks as the Tertiary formations. 

This was also the first French work which adopted the - 
method introduced by William Smith in England ten years 
previously, of determining the respective ages of the rocks by 
means of the fossils contained in them. And in this sense the 
work had a revolutionary effect on French geology. 

In a later publication Brongniart extended his observations 
to the fresh-water deposits of other neighbourhoods Orleans, 


Le Mans, Aurillac, and Limagne. Brard covered a wider field 
of research, and added still further to the investigation of the 
fresh-water deposits and their fossils (Annales du Museum, 
1809, 1810). 

The zoologist, De Ferussac, made a special research of the 
molluscan species in the fresh-water limestone near Mainz, in 
Quercy, and in Spain. His publications in the Memoirs of 
the Institute (1812 and 1813) proved that of about eighty-five 
species nearly all had become extinct; a few, however, could 
be identified with species still living in distant neighbourhoods 
or indigenous to Central Europe. Ferussac confirmed Brong- 
niart in his opinion that the molluscan species could be used 
to determine the age of fresh-water deposits. 

So much interest had been aroused in these Oligocene 
deposits that Omalius d'Halloy, 1 the Belgian geologist, made 
an examination of the series in Auvergne, Velay, and in parts 
of Italy and Germany, and in all cases proved conclusively 
that the fossil remains had been imbedded in the deposits of 
fresh-water marshes, and were not remains which had been 
accidentally swept into marine deposits. 

The Belgian geologist supplemented the observations of 
Cuvier and Brongniart with great success. With unceasing 
diligence, he conducted geological tours on foot during ten 
years, and as a result he was enabled to produce a geological 
map of France and the adjoining territories of Belgium, 
Germany, and Switzerland. The map gave a faithful represen- 
tation of the distribution of the leading geological formations. 
It was first published in 1822, on the scale of i 14,000,000, 
and was in later years improved and incorporated in D'Halloy's 
Text-book of Geology. 

Early in his career, D'Halloy had regarded the position of 
the strata, their horizontal, slightly or highly inclined, or 
vertical position, of great importance in determining the age 
of the strata. He thought the horizontal strata corresponded 
to Werner's " Flotz formations," and all inclined strata to 

* Jean Baptiste Julien d'Omalius d'Halloy, born 1783 in Liege, the only 
son of a rich aristocratic family, came under the influence of Brongniart, 
Cuvier, Faujas, and Lamarck in Paris; he devoted himself from 180410 
1814 wholly to the pursuit of geological researches in France, Belgium, 
and the neighbouring districts; in 1815 was appointed Governor of the 
Province of Namur; afterwards a Member of the Belgian Senate, and 
President of the Academy of Sciences in Brussels; died 1875. 


Werners " Transitional formations." But his subsequent visit to 
the Alps and Jura mountains caused him to modify these views. 

He accomplished new and important work of investigation 
in the Carboniferous districts of Belgium and the Rhine Pro- 
vinces. He showed the extensive development of the highly- 
tilted slate formation in the Ardennes, the Eifel and Hunsriick, 
and pointed out that in the Rhine Province and in the Pala- 
tinate (Pfalz) this formation had been penetrated by volcanic 
rocks. The productive horizons were chiefly developed in the 
northern French provinces, Artois and Boulonnais, while the 
fossiliferous strata beneath the coal-bearing series were best 
developed in the Hennegau. Thus Omalius d'Halloy laid the 
foundation of geological knowledge over wide areas. His 
more detailed works are those which deal with the Tertiary 
deposits of the Paris basin. He united horizons 5 and 7 in 
the classification system of Brongniart and Cuvier, and traced 
the topographical distribution of each horizon. 

The hill of Petersberg, near Maestricht, was made the subject 
of a local monograph of high excellence by Faujas de Saint- 
Fond. The chalk series of this district has since been recog- 
nised as the uppermost horizon (" Danian Stage") of the 
Cretaceous formation, a stage absent in the British develop- 
ment, but of very great interest from the intermediate 
Cretaceous-Eocene character of the fauna. 

The monograph of Faujas de Saint-Fond begins with a 
description of the hill and the deposits, more especially the 
system of caverns and tunnels that had been excavated in the 
rock. In the palaeontological portion, the first specimen 
described is the huge reptilian skull, Mosasaurus Camperi, 
that had bee-n found in these deposits in 1770. The specimen 
originally belonged to a physician of the name of Hoffmann, 
but, as the result of a lawsuit, it came into the custody of the 
Canon Godin, and finally, after the siege of Maestricht by the 
French in 1795, it was demanded as booty of war and trans- 
ferred to the Paris Museum. The famous anatomist, Peter 
Camper, had examined the jaw of a similar fossil animal and 
identified it as the remains of a Cetacean, nearly allied to the 
genus Physeter, whereas Faujas tried to demonstrate that it 
represented a fossil crocodile. Both indications were proved 
erroneous by Cuvier, who identified the remains as those of a 
marine serpent-like reptile, and placed the genus Mosasaurus 
among the lizards, in near relationship to the genus Varanus. 


Other remains from the Maestricht chalk that had been 
erroneously classified by Faujas and his predecessors were 
some large marine chelonians, which Cuvier again was the 
first to identify correctly. 

Faujas' descriptions and illustrations of Invertebrate groups 
were particularly good. Only the want of an adequate 
scientific terminology, distinguishing the original specimens 
according to genus and species, has prevented the monograph 
from taking a permanent place in the works of posterity, as it 
must otherwise have done. Faujas himself seems to have had 
no further aim in view than to show how important the 
accurate description of the fossils of one limited locality might 
be for palaeontology and geology, inasmuch as these descrip- 
tions could be used as a definite basis of comparison with the 
fossil remains in other localities. 

There is little to relate about the geology of the Iberian 
Peninsula at this period. After the brilliant successes 
achieved by the Spanish and Portuguese mariners in the fif- 
teenth and sixteenth centuries the sciences became neglected, 
more especially the natural sciences. The first work devoted 
to Spanish fossils in the Spanish language was written by 
a Franciscan father, Jose Torrubia (The Natural History of 
Spain, 1754). The author had travelled in America and the 
Philippines, and had collected fossils and minerals from 
various lands. He drew up a complete list of all localities 
where fossils had been found, and gave illustrations of the 
Spanish fossils on fourteen large plates,. Minor works were 
published on local physical and geographical relations by 
Bowles, an Englishman resident in Spain, and by the Spanish 
botanist, Cavanilles, on the occurrence of fossils in the province 
of Valencia. 

E. Great Britain. Researches into the constitution and 
history of the earth were always held in high regard in Great 
Britain. The natural wealth of the country in coals and useful 
minerals, the early development of mining and smelting, the 
frequent discovery of well-preserved fossils, had all contributed 
to awaken widespread interest in a knowledge of rocks. Many 
who had less sympathy for the scientific aspect of the subject 
found themselves attracted by the literature that was called 
forth in the effort to bring each new geological fact as it came 
to light into harmony with the tenets of Biblical inspiration. 


Thus, in addition to strictly empirical writings, there grew up 
an independent speculative literature in which the names of 
Whiston, Burner., and Woodward are prominent. 

Towards the end of the eighteenth century, in 1789, John 
Williams, director of mines, published a Natural History of 
the Mineral Kingdom, with a description of the coal-beds and 
their occurrence in Great Britain, which was remarkably com- 
plete. Williams was a violent opponent of Hutton, whom he 
blamed for disbelief in the Deity. 

The hazy suggestions of Robert Hooke and others, that 
fossils might perhaps be of use in identifying the chronological 
order of the rocks, had remained unheeded for more than 
a century. The greatest stratigraphers on the Continent, 
Lehmann, Fiichsel, Arduino, had directed their attention far 
more to the constitution of the rocks than to any benefit that 
might be derived from a study of fossils. Giraud Soulavie 
and Buffon had conceived some idea of the floras, but had not 
ascertained any sure method of applying such variations to 
problems of historical geology and stratigraphy. 

William Smith, 1 an English engineer, was the first to 
recognise the importance of fossils in their full significance as 
a means of determining the relative age of strata. Born in a 
county that was unusually rich in fossil remains, he had in his 
boyhood abundant opportunity of observing and collecting. 
As assistant to a land-surveyor he became intimately acquainted 
with the counties of Oxfordshire and Hampshire, and with the 
surroundings of Salisbury and Bath. 

1 William Smith, born on the 23rd March 1769, at Churchill in Oxford- 
shire, son of a farmer, received a scanty elementary education at the village 
school ; managed, however, to train himself to some extent in geometrical 
studies, and entered at the age of eighteen as an assistant in a land- 
surveyor's office. He was afterwards employed as engineer in the con- 
struction of a canal in Somersetshire, and practised independently as land- 
surveyor and civil engineer. He lived in London from 1801 to 1819; in 
1828 he became factor for the estates of Sir John Johnstone. After the 
Geological Society was founded, William Smith was in 1831 the first 
recipient of the Wollaston medal; in 1835 the University of Dublin made 
him an honorary Doctor of Laws ; and in 1838 he was a member of the 
commission for the building material of the Houses of Parliament. During 
the later years of his life he was in poor circumstances ; a small pension 
was granted to him by the Government, and he died unmarried at 
Northampton in 1839. (Biography of William Smith in Sedgwick's 
Presidential Address, Proc. Geol. Soc. London, 1831, p. 279; John Phillips, 
Memoirs of William Smith , 1844.) 


In 1791 he observed the agreement of the red marl and the 
Lias near Bath with the corresponding strata in Gloucester- 
shire, and also their unconformable position upon the 
Carboniferous formation. For twenty-five years William 
Smith continued his investigations in all parts of England ; 
he entered his observations in coloured geological maps, and 
compiled them from time to time in the form of tables or as 
explanatory notes to his maps. He also carried out a scheme 
of arranging a collection of fossils according to the succession 
of strata ; his own collection was acquired by the British 
Museum, and is still exhibited there. After his long period 
of field observations, William Smith came to the conclusion 
that one and the same succession of strata stretched through 
England from the south coast to the east, that each individual 
horizon could be recognised by its particular fossils, that 
certain forms reappear in the same beds in the different localities, 
and that each fossil species belongs to a definite horizon of 

Like his famous contemporary Werner, William Smith also 
had a disinclination for writing; on the other hand, he was 
always willing to communicate the results of his investigations 
orally. It is told of him how in the year 1799 he made the 
acquaintance of the Rev. B. Richardson, in Farley, who owned 
a large collection of fossils from the neighbourhood of Bath. 
To Richardson's astonishment, Smith knew better than the 
owner himself where the individual species had been found 
and in which particular horizon of rock. 

Then a dinner was arranged, at which William Smith met 
another enthusiastic fossil collector, Rev. W. Townsend, and 
William Smith consented to dictate a table of the British strata 
from the Carboniferous to the Cretaceous formation. The 
table of strata was rapidly copied and distributed among 
geologists. The original manuscript, written by Richardson 
and dictated by Smith, is in the possession of the Geological 
Society in London. In this first table of Smith's the successive 
strata were indicated by numbers. 

But Smith was not content with the determination of a 
chronological succession of strata; he traced their surface 
outcrops, and thus built up the material for his maps and 
sections. He laid before the Board of Agriculture a 
series of memoranda and geological maps which were 
published between 1794 and 1821 in the form of 


excellently printed detail-maps of fifteen counties. These 
maps were on such a large scale, and so full of details, that 
they had a limited circulation. Smith therefore conceived a 
plan to publish a geological map of England and Wales on a 
small scale, that should show accurately the course of the 
surface outcrop of each stratigraphical horizon, and should be 
accompanied by geological sections to the true scale of the 
map. The preliminary sketch of this plan was drawn up in 
1 80 1, and may be seen in the Archives of the Geological 
Society; but it was 1812 before Smith found a publisher to 
undertake the map. In 1815, the famous map of England 
and Wales appeared, consisting of fifteen sheets in the scale 
of i inch to 5 miles. The complete map is 8 ft. 9 in. high 
and 6 ft. 2 in. broad. The individual strata are indicated 
by different colours, and sometimes the basis of a stratum is 
marked by a darker line of the ground colour. 

Smith's map is the first attempt to represent on a large 
scale the geological relations of any extensive tract of ground 
in Europe. It was a magnificent achievement, and was the 
model of all subsequent geological maps. For English 
geology, the publication of the map was the starting-point of 
a new regime. Smith gave an explanatory text of fifty 
pages, in which he introduced a stratigraphical terminology 
adopted from the local names in practical use (Lias, Forest- 
Marble, Cornbrash, Coralrag, Portland Rock, London Clay, 
etc.), and these names of horizons have for the most part been 
retained in geology to the present day. 

Between 1816 and 1819, Smith began a work entitled 
Strata identified by Organised Fossils, containing prints of the 
most characteristic specimens in each stratum. Four volumes 
appeared containing the description of sixteen strata and 
their characteristic fossils, from the horizon of Fuller's Earth 
to London Clay, but the work was never completed. In 1817 
he prepared an ideal geological section across England from 
London to Snowdon, and the section was afterwards intro- 
duced into most text-books. A contemporaneous account of 
Smith's results and his terminology was published in 1818 in 
a small book written by William Phillips. 

William Smith was a self-taught genius of rare originality 
and with exceptionally keen powers of observation. Without 
much intellectual cultivation, without any introductory 
teaching, without any means at his disposal, and at first even 


without the encouragement and sympathy of colleagues in the 
study which he loved, his own unflinching determination, 
noble enthusiasm, and remarkable insight enabled him to 
elucidate the structure of his native land with such clearness 
and accuracy that no important alteration has had to be made 
in his work. Smith confined himself to the empirical 
investigation of his country, and was never tempted into 
general speculations about the history of formation of the 
earth. His greatness is based upon this wise restraint and 
the steady adherence to his definite purpose; to these 
qualities, the modest, self-sacrificing, and open-hearted student 
of nature owes his well-deserved reputation as the " Father of 
English Geology." 

Soon after their publication, Smith's researches were 
productive of results which he could never have anticipated. 
It was found that the strata described by him from the Lias 
to the Purbeck horizons filled the great gap between the 
Muschelkalk and the Cretaceous formations in Werner's 
system. European geology was thus enriched by the accurate 
knowledge of an important series of fossiliferous geological 
horizons, and the equivalents of the English Lias, Cornbrash, 
Portland and Purbeck series were sought for and discovered 
in various parts of Europe. 

George Greenough, 1 the founder of the Geological Society of 
London, published a geological map of England and Wales 
in 1819, soon after the appearance of W. Smith's. The 
topographical groundwork and technical workmanship of 

1 George Bellas Greenough, born 1778, at first studied law at Cambridge 
and Gottingen, but under Blumenbach's guidance turned to natural science, 
and afterwards studied mineralogy and geognosy with Werner in Freiberg ; 
travelled in Germany and Italy; became a Member of Parliament in 1807, 
and in the same year, on November I3th, founded the Geological Society 
of London ; died 1855 in Naples. The Geological Society has exer- 
cised a strong and favourable influence upon the development of geology 
in England. The aim in founding the Society was to unite all the English 
geologists, and to keep alive and encourage the interest in. geology by the 
regular publication of memoirs, Transactions, and shorter reports of the 
communications made at the meetings. The first of six volumes of Trans- 
actions appeared in 1811. Much later, in 1845, the Transactions, published 
in quarto form, were replaced by the Quarterly Joiirnal, fifty-two volumes 
of which have now been published, and have upheld the high quality 
of the Society's publications. Mr. Greenough, the first President of the 
Society, helped very considerably to supply the means for endowment of 
the Geological Society. 


e J c 


Greenough's map were particularly good ; the geological 
colouring embraced Smith's results, and was partially founded 
upon his own observations. The original edition appeared in 
six sheets; in 1826 a reduced map was published and at once 
obtained a wide circulation. New and improved editions of 
Greenough's map continue to appear at the present day, and 
for a long time this map was the best that existed. 

Smith's example gave a new impulse to geological work. 
John MacCulloch, 1 a physician in private practice, gave up his 
practice and devoted himself between 1811 and 1821 to the 
geological investigation of Scotland. The first fruits of his 
important labours were published in 1819 in his Description 
of the W.I. of Scotland. In 1826 he was commissioned by 
the Minister of Finance to prepare a geological map of that 
country. This large undertaking was completed in 1834. 
There were, however, no detailed topographical maps of 
Scotland available at that time, and MacCulloch had to enter 
the geological colours on the meagre topographical basis of 
the Arrowsmith map. MacCulloch's map was published 
posthumously in 1840. It frequently passed under the name 
of the author of the topographical map, and received on its 
appearance little attention even from geologists. Nevertheless, 
MacCulloch was one of the pioneers of British mineralogy and 

The country which he investigated was bristling with com- 
plexities and difficulty of every kind, but a wide mineralogical 
knowledge and experience stood him in good stead, and he 
built up a thorough groundwork for the general features in the 
distribution of the rock-varieties in Scotland. Although a 
little unwillingly at first, owing to MacCulloch's personal 
peculiarities and unpopularity, his memoirs have long been 
recognised as classical works in the history of British geology. 
They are characterised by accurate mineralogical determination 

1 John MacCullcch, born 1773 in the island of Guernsey, of Scotch 
descent, was educated in Cornwall, and studied medicine in Edinburgh. 
He became so enamoured of mineralogical studies that in 1811 he gave up 
his practice, and in the same year he communicated to the Geological 
Society several papers on the structure of the Channel Isles and Heligoland. 
In 1814 he was appointed a geologist on the Trigonometrical Survey. He 
belonged to no particular school ; he frequently fell into scientific disputes 
with his contemporaries, and was very unpopular on account of his per- 
emptory way and jealous temperament. He died in 1835, through a 
carriage accident in Cornwall. 



of the rocks, and by their extraordinary number of careful 

Farey published a General View of the Agriculture and 
Minerals of Derbyshire in 1815, with geological sections and 
maps. Thomas Webster and Professor William Buckland 1 
studied the character and distribution of the younger sedi- 
mentary rocks of England. Buckland described in detail 
the pebble and sand deposits above the Tertiary formations 
and below the very youngest fluviatile, lacustrine, or marine 
deposits. He identified the widely-distributed pebble-beds 
with the epoch of the universal Deluge, and called them 
Diluvial detritus; the youngest deposits he termed Post- 
diluvial (alluvial) detritus. He also made a large collection of 
fossils from the Liassic and Oolite series in the Midlands, and 
followed William Smith's initiative in working out successive 
horizons upon palaxmtological evidence. Buckland's system 
of the Secondary formations, more especially of the Jurassic 
formation, has remained a model of clearly-defined paUeonto- 
logical horizons of strata. 

The magnificently-formed basaltic pillars of StafTa, the 
Giant's Causeway, and County Antrim early attracted notice. 
Pennant's Book of Travel (1774) gave descriptions and illus- 
trations of these, without attempting any explanation of their 
origin. John Whitehurst (1786), the Rev. William Hamilton 
(1790), and Abraham Mills (1790) advanced the idea of a 
volcanic origin, and Faujas de Saint-Fond, after a journey in 
Scotland and Ireland, supported this explanation. 

On the other hand, Kirvvan (1799) and the Rev. William 
Richardson (1808) reported the discovery of fossils in the 
basalt of Ballycalla, near Portrush, and consequently advocated 
the aqueous origin of basalt, trap, granite, etc.; but Playfair 
proved that the supposed fossiliferous basalt of Portrush was 
only metamorphosed Lias. 

Contributions to the geology of Ireland were made by 
Conybeare and Buckland (1813), Vaughan Sampson (1814), 

1 William Buckland was born 1784, the eldest son of the Rev. Charles 
Buckland, at Axminster, in Devonshire ; studied theology in Oxford, and 
was a Fellow of Christ's College there. In 1813 he was appointed 
Professor of Mineralogy, and in 1819 was made in addition the first Pro- 
fessor of Geology in Oxford ; in 1845 he became Dean of Westminster. 
He died 1856, held in the highest respect and esteem by all English 
geologists. (The Life and Correspondence of William Buckland, by his 
daughter, Mrs. Gordon; London, 1894.) 


and Dr. J. T. Berger, of German birth, who had been trained 
in Werner's school. Berger's description of the. geology of 
N.E. Ireland, published in 1816, with a preface by Conybeare, 
has proved fundamental in the geological literature of that 
country, while the geological maps of Ireland, published by 
Richard Griffith in 1834 and 1838, afforded a complete general 
survey of the stratigraphy. 

In Scotland, Robert Jameson (1774-1854), an enthusiastic \ 
pupil of Werner, tried to establish Neptunian doctrines. He j 
founded a Wernerian Natural History Society in Edinburgh, 
wrote a Text-book of Geognosy upon Werner's principles, 
and was for fifty years Professor of Geology in Edinburgh 
University. He and his students made many valuable 
researches in Scottish mineralogy, petrography, and geognosy, 
but their biassed Wernerian view of the rock-formations 
prevented them from attaining any real insight into the 
complex stratigraphical relations of the sedimentary deposits 
in Scotland. 

Hutton strongly opposed the Neptunian teaching of 
Jameson, which was contrary to all his experience in Scotland. 
On one occasion in 1783, when Hutton was on a visit to the 
Duke of Athole, he happened to observe red granite dykes 
near Glen Tilt, in the Grampians, penetrating black mica 
schist and limestone. He was so overjoyed at the sight that 
his companions could not understand what was the matter, 
and thought Hutton must have discovered a gold-mine in the 
rocks ! Afterwards at Cat's Neck, Hutton saw dykes of trap- 
rock intruded in all possible directions through sandstone. 
These observations formed the basis of his paper " On 
Granite," wherein he proves that granite is frequently younger 
than sedimentary aqueous deposits. John MacCulloch 
brought subsequent confirmation of Hutton's views by 
showing that intrusive dykes of basalt, porphyry, granite, and 
other varieties of igneous rock, abound in the Western Isles of 
Scotland, and that the stratified deposits have been altered at 
zones of contact. 

F. Scandinavia and Russia. The first Scandinavian scholar 
who interested himself in the history of the earth was Urban 
Hiarne (1641-1 724). His work, published in 1694, draws its con- 
ceptions of the earth's interior chiefly from Athanasius Kircher. 
While he recognised fossils as the remains of organisms, he 


supposed these organisms had come into existence after the 
Deluge. To the epoch of the Deluge he also attributed 
gigantic disturbances of the earth's surface that had uplifted 
great portions of Scandinavia and thrown other areas into the 
interior of the earth. He thought that frequent recurrences 
of disturbance had taken place, elevating and destroying 
mountain-systems and continents. 

Hiarne's work was written in his own language, and was little 
read outside Sweden. The scientific writings of Emanuel 
Swedenborg, the religious enthusiast, were more widely read. 
Swedenborg (1688-1772), who held for a long time the post of 
Assessor of Mines in Sweden, took a great interest in fossils, 
and in his Observations of Natural Things (1722) he 
mentions and describes a large number of Swedish fossils. 
He thought the fossils found in high tablelands and mountains 
had been left there by the flood ; he regarded the trap-rocks 
(Swed. trappa, a stair, from the characteristic weathering) as 
aqueous sediments, and referred volcanic phenomena to the 
presence of molten reservoirs within the solid crust of the 

A work devoted to palaeontological details was published in 
1727 by Magnas von Bromell; his Lithographia Suecana 
treats of trilobites, corals, and gastropods from Gothland, and 
of graptolites and plant-remains in calcareous tuff. Another 
author, Kilian Stobseus, described the first known Ammonites 
and the so-called "Brattenburg pennies" from the Cretaceous 
deposits of Schonen. The year 1743 was signalised by the 
publication of the famous observations made by Anders 
Celsius on the sinking of the sea-level in the Gulf of Bothnia. 
Celsius reckoned the lowering of the sea-level at 450 ft. in 
10,000 years. 

Carl von Linne (1707-78) published in 1756 his account 
of a geological tour that he made as early as 1741 with six 
students to Oeland and Gothland. At West Gothland Linnaeus 
had investigated very carefully the horizontal strata of the 
"transitional formations" (now identified as Silurian and 
Cambrian), succeeded by a series of trap-rocks well exposed at 
the Kinnekulle hill. A typical section through the Kinne- 
kulle hill was drawn up by Johan Svensson Lidholm, under the 
guidance of Linnaeus, and it was taken as a standard for 
the stratigraphical relations throughout Sweden. Linnaeus 
assigned the trap or igneous series to aqueous origin. In 


1749 he examined the Cretaceous rocks in Schonen, and in 
the last edition (1768) of his Systema Naturcc he gave a 
complete list of the fossils known to him, and arranged them 
according to their occurrence in his system of the rock 
succession. He arrived also at remarkably clear conceptions 
about the accumulation of different kinds of sedimentary 
deposit upon the floor of the ocean. 

While Linnaeus was a true empirical observer, and may be 
regarded as the founder of constructive geology in Sweden, a 
contemporary of his, Tobern Bergman (1735-84), inculcated 
theories regarding mineral structure and the constitution of 
the earth's crust which were largely adopted by Werner, and 
were thus destined to wield a European influence. His 
Physical Description of the Globe (1769) was translated into 
German, and was the foundation of the Wernerian doctrine 
that the earth's crust was composed of successive strata of 
different thicknesses and constitution, but uniformly envelop- 
ing the spherical earth ; further, that these have arisen as 
chemical precipitates, and not simultaneously, but gradually 
during protracted epochs of time. In addition there were 
deposits accumulated by mechanical means and volcanic 
rocks. He classified the rock-succession in four sub-divisions : 

(1) Primitive rocks, comprising the chemical precipitates; 

(2) the Flotz series, comprising sediments of mechanical 
origin ; (3) transported rocks ; (4) volcanic rocks. 

Daniel Tilas (1712-72) made a special study of the erratic 
blocks and superficial pebble -beds of Sweden. He wrote 
strongly on the importance of petrography, and to his warm 
advocacy Sweden doubtless owes the preparation of its earliest 
geological maps: the map of West Gothland by Hisinger in 
1797, and the maps of Nerike, Schonen, West and East 
Gothland by Gustaf Hermelin, published between 1797 
and 1807. Both these authors contributed an explanatory 
text to their maps, and thus laid the basis of stratigraphy in 
Sweden, Hisinger (1766-1825) wrote a general description of 
the mineralogical relations of Sweden; and the second edition, 
soon after its appearance in 1808, was twice translated into 
German. This work contains a historical review of all the 
facts known about Swedish rocks up to that date, and applies 
Werner's systematic arrangement. 

The oldest information about the geography, minerals, and 
rocks of Norway is to be found in Erich Pontoppidan's Natural 


History of Nonvay^ 1753. In the beginning of the nineteenth 
century, Werner's scholar, Jens Esmarch, conducted mineral- 
ogical investigations in Norway. J. L> Hausmann travelled 
through Scandinavia in 1806 and 1807. His chief aim was to 
investigate the mining districts of Sweden and Southern Nor- 
way, and his account of the journey, which was published 
several years later, contains a large number of valuable observa- 
tions on the minerals and ores of these districts. It also 
embraces detailed descriptions of the Cambrian rocks near 
Andrarum, the famous section at Kinnekulle, and other features 
of geological interest. Hausmann was the first scientific 
observer who noted the position of the granite above the 
"transitional" limestone formation in the neighbourhood of 
Christiania, and the first who described the zircon syenite of 
the Langensund (cf. p. 86). 

But Leopold von Buch's Journey to Norway and Lapland 
(Berlin, 1810) was the work which first gave European geolo- 
gists an insight into the general geological structure of Norway. 
The novelty of many of the districts traversed, and the author's 
genius for the narration of scientific observations, combined to 
secure immediate popularity for this work. 

On the journey to Scandinavia, Leopold" von Buch passed 
through Mecklenburg, Hamburg, Holstein, and Copenhagen. 
He gave full notes about the erratic blocks, and the white 
chalk of Moen and Stevensklint. The journey to Christiania 
was carried out by land, the route leading across the Swedish 
seaboard and the coast of the Christiania Fjord. Von Buch 
confirmed Hausmann's observation that not granite but gneiss 
was the predominating rock in this district. He was also 
greatly struck by the relations between the transitional rock- 
formations and the granite-grained rocks. He described the 
various kinds of rock, and showed that the porphyry penetrated 
the " transitional " formations as dykes and veins, and that be- 
tween Drammen and Christiania a large mass of granite rested 
upon fossiliferous "transitional limestone." This occurrence 
was at once admitted by Buch to be incontestable evidence 
that granite was not, as Werner had taught, in all cases part of 
the oldest rock-formation, although he still clung to the idea of 
the aqueous origin of the porphyritic and granitic series. In 
1808, Leopold von Buch travelled through the northern terri- 
tories of Norway and Lapland. He took geological observations 
at the Dovre Feld Mountain in Drontheim, at Lake Mjosen, 


and in Gulbrand Valley; and wherever he travelled he gave 
attention to the climatic conditions, and to the habits and 
cultivation of the people. Near the town of Drontheim, 
Buch saw a coarse-grained diallage rock, which he afterwards 
recognised again in the Alps of Valais, in Tuscany, the Riviera, 
and other places; he described it under the name of "gabbro." 
He observed the diallage rock together with slate at the North 
Cape. His numerous observations on upraised beach deposits 
round the northern coast-line of Norway led him to conclude 
that the uprise in Sweden had been greater than in Norway, 
and had been altogether greater in the north than in the south 
of the peninsula. 

In Russia, the numerous remains of land mammals, 
especially the mammoth and rhinoceros, had long attracted 
attention. One of the chief aims of Johan Georg Gmelin's 
expedition to Siberia was to look for complete remains of these 
animals and bring them to St. Petersburg (Reise durch Siberien> 
1752). Pallas was, however, the scientist who most success- 
fully carried out this purpose, and his works were the means of 
opening up to science the geological structure of the vast 
Russian empire. The collective works of Georgi and Razu- 
mowsky, as well as the first geological map of Russia by 
Strangways, are largely based upon the researches of Pallas, 
and partially upon the independent investigations of these 

G. America, Asia, Australia, Africa. Although no country 
outside Europe bore any appreciable part in the construction of 
the early framework of the science, it was a matter of keen 
interest to geologists to compare the structures ascertained in 
Europe with those in other regions of the globe. All observa- 
tions of the mineral constituents and structural forms in other 
parts of the world were much valued at home, and in many cases 
were employed as corroborative evidence in favour of one theory 
or another. In the beginning of the nineteenth century but 
little was known in Europe of the geology of foreign parts, yet 
what was known sufficed to show that the results obtained in 
Europe were in harmony with geological phenomena elsewhere, 
and might therefore be regarded as a sure scientific basis for 
future progress. 

The errors, the false hypotheses, and bitter disputes which 
had retarded the growth of the science during many centuries 


in Europe, were spared in the case of the other continents. 
In them the knowledge so hardly won in Europe could at 
once be adopted, and the help of experienced European 
observers could be secured in carrying out pionner research 
elsewhere. Thus geological data furnished within a few years 
in foreign lands could often bear comparison with the results 
that had demanded many decades or even centuries of work 
in the European territories. Active co-operative research in 
the other continents did not commence until after the period 
with which this introductory chapter deals. 

North America was first brought into the field of geological 
science. As early as 1752, Guettard had examined a collec- 
tion of Canadian fossils, and had tried to apply to North 
America the sedimentary horizons which he had erected for 
Europe. He had gone so far as to construct a hypothetical 
map showing the distribution of the various rock-formations 
whose existence he had surmised. 

Of another character were the investigations of the Scots- 
man, Maclure (1763-1840), who had been trained as a 
mineralogist by -Werner. Maclure published in 1809 a treatise 
and a map on the geology of the United States (Trans. A/ner, 
Phil. Soc.). He distinguished the rock-formations according to 
Werner's system, and showed that the primitive rocks pre- 
dominate on the north and west of the Hudson, and form the 
basement in the New England States; the transitional forma- 
tions repose upon the primitive rocks and extend far west to 
the Mississippi, where the Flotz or younger sedimentary forma- 
tions begin. Maclure also gave a clear exposition of the 
distribution of the Carboniferous formation in the Alleghanies, 
in Pennsylvania, and in the West, of the absence of trap-rocks 
in the Flotz formation, and the absence of porphyry, vesicular 
rocks, and basalt in the whole eastern district of the United 
States. He fully realised and depicted the simplicity and the 
gigantic scale of geological structures in the United States. 

Maclure's comprehensive survey of the geology of North 
America overshadows the many smaller works on local strati- 
graphical details, such as those of Jefferson, Gibbs, Bruce, 
JSilliman, and others. 

Long before geological research had begun in North America, 
however, the presence of mammalian remains similar to those 
of Siberia had been discovered. Dr. Mather, in 1712, reported 
in a letter to Woodward the presence of bones of enormous 


size near Albany (New York), and surmised that they must 
have belonged to a race of giants. In 1739, a French officer, 
Longueil, brought back to Paris fossil bones and teeth found 
in a marsh near Ohio. Daubenton and Buffon identified 
the bones as Elephas and the back teeth as Hippopotamus 
remains. More complete fossil remains were discovered by 
Croghan and Peale, and the restoration of a skeleton was 
attempted. Cuvier, with his customary insight, recognised in 
this an extinct genus of Proboscidae, to which he gave the 
name of Mastodon. His great work on Mastodon gives a full 
account of all the remains of this extinct genus that had been 
found up to that time in North America. 

In a cave in West Virginia, Jefferson discovered along with 
Mastodon remains the extremities of another diluvial animal. 
Cuvier examined these, and referred them to a gigantic genus 
(Megalonyx) belonging to the Edentates. 

Throughout Mexico, Yucatan, Bolivia, Peru and Chili, fossil 
bones of enormous size had been frequently found during the 
sixteenth and seventeenth centuries. In 1789, Loretto, the 
Regent of Buenos Ayres, sent a complete skeleton of one of 
these fossil animals to Madrid, and shortly after, two other 
skeletons were sent from Lima and Paraguay. These were 
described by J. Garriga under the generic name of Mega- 
therium; they were found to belong to the Edentates, and, 
like Megalonyx, to the sub-order Gravigrada. Garriga's iden- 
tification was afterwards confirmed by Cuvier. The first 
remains of a Glyptodon, another of these heavily-built fossil 
Edentates, are mentioned by the Jesuit Falkner in the account 
of his travels. 

Alexander von Humboldt's observations were the earliest 
contribution to the geology of Central America. This great 
geographer applied Werner's system of rock-formations, and 
wherever he travelled in Central and South America identified 
the rocks in accordance with Werner's petrographical teaching. 
He thought that the distribution of the rocks in these regions 
fully confirmed Werner's chronological succession of the groups 
of formations. 

In Asia, the pioneer work of Pallas in Siberia and the Urals 
was continued by Patrin, who published in 1783 the Account 
oj his Travels in the Altai Mountains. The geological struc- 
ture of Central and Southern Asia, Australia, and Africa was 
still a blank in the beginning of the nineteenth century. The 


few reports that had been given by travellers merely con- 
firmed the presence of volcanoes in one locality or another, 
or mentioned the occurrence of the more striking varieties of 

Progress of Petrography Neptunists, Volcanists^ and Plu- 
tonists. In the older mineralogical literature the rocks also 
received a passing notice. As a rule, authors limited these 
remarks to a description of their external features. Cronstedt 
removed them from this subordinate position, and paved the 
way for Werner's creative work in establishing the study of the 
rocks as an independent branch of Geognosy. Werner's 
classification and description of rock-varieties, published in 
1786, comprised all existing knowledge of rocks, and replaced 
the vague conceptions of former years by a series of exact 
definitions and the introduction of a new, precise nomen- 
clature. Werner distinguished simple and composite rocks ; 
the former were discussed both as minerals and rock-forms, 
e.g. quartz, gypsum, salt, etc., the latter were identified and 
classified according to their mineralogical composition and 
their age, e.g. granite, basalt, sandstone, marl, etc. 

Each rock was defined in respect of its texture, stratigraphical 
position, jointing, age, origin, and occurrence. In the case of 
composite rocks, the essential components were distinguished 
from the accessory and the rock was classified solely upon the 
ground of the essential components. 

The rapid advance of petrographical knowledge during the 
first two decades of the nineteenth century was undoubtedly 
the direct result of Werner's precise methods. All observers 
during those decades gave marked attention to the determina- 
tion of petrographical features. Saussure's descriptions of the 
crystalline massive and schistose rocks in the Swiss Alps can 
scarcely be surpassed. Monographs appeared from time to 
time on special varieties of rock. Faujas de Saint-Fond, for 
example, wrote a monograph on the "trap-rocks," in which he 
showed how loosely this name had been applied in the litera- 
ture, so that rocks of many different kinds were embraced 
under it. 

Ferber and Dolomieu investigated the volcanic products of 
Southern Italy. Desmarest, Faujas, and others examined the 
Egyptian porphyries and so-called basalts. Leopold von 
Buch introduced the name of gabbro^ and described leucite 


lavas and trap-porphyry (trachyte) in detail; while Hauy 
introduced the names of pegmatite, diorite, trachyte, aphanite* 
euphotide, leptinite. 

Brongniart attempted a complete classification of rocks in 
1813, and introduced the terms diabase, melaphyre, psammite, 
etc. Fleurien de Bellevue and Cordier made use of the micro- 
scope for the identification of the components in powdered 
specimens, but with little success. 

The advances made in these early decades practically repre- 
sented the progress that could be attained by the use of 
Werner's method. A new era began for this branch of geology 
when, in later years, the microscope was applied to the examina- 
tion of thin rock-sections by transmitted light. 

Very great interest centred round the origin of the massive 
crystalline and schistose rocks, and widely divergent opinions 
were held. The Neptunists thought that all' rocks, with 
the exception of products from active volcanoes, were of 
aqueous origin. At first the Neptunists and Volcanists dis-< 
puted only the origin of basalt, which Tobern Bergman, and 
afterwards Werner and his school, regarded as a sedimentary 
rock. Almost all French geologists had studied basalt in 
Auvergne, Velay, Vivarais, or in Ireland, and adopted the 
view of Desmarest and Faujas de Saint-Fond, that basalt was 
a volcanic product. 

In Germany, Werner's personal influence kept alive Nep- 
tunian doctrines even against sharp attacks like those of Voigt 
(p.- 83). Not a few of the German geologists began to assume 
an intermediate position. Beroldingen tried to unite the 
opposite gpinions by suggesting that basalt owed its origin 
to volcanism, but its form to water. The basaltic magma had 
solidified on the bed of the ocean, and its pillared, sheet-like, 
spheroidal, or crystalline form had been developed under the 
influence of water and hot vapours. In favour of this view, 
Beroldingen cited the local occurrence of Ammonites, Gryph- 
ites, and Belemnites in basalt. This observation was, however, 
afterwards found to have been erroneous. Yet in the course 
of his discussion, Beroldingen gave expression to many valu- 
able remarks about volcanic ejecta and the disintegrating 
changes undergone by volcanic rocks. C. W. Nose, an 
observer who greatly advanced the geology of the Lower 
Rhine provinces of Prussia, was of the opinion that basalt 
and porphyry originated as sedimentary deposits, but were 


subsequently more or less altered, sometimes even fused and 
rendered glassy or slaggy. 

When, after Werner's death, his two most famous pupils, 
Leopold von Buch and Alexander von Humboldt, declared 
themselves in favour of the volcanic origin of basalt, the 
defeat of the strict Neptunists was sealed. A historical account 
of the whole question of basalt, and the disputes between 
Neptunists and Volcanists, may be read in Keferstein's 
Contributions to the History and Knowledge of Basalt (1819). 

But Neptunian doctrines still continued to be accredited for 
granite, syenite, gneiss, and other members of the holo- 
crystalline series. Descartes, Leibnitz, and Buffon had cer- 
tainly explained the primitive earth-crust as the result of 
cooling from a molten mass, but they had made no attempt 
to explain the origin of the various kinds of primitive rock. 
It was generally supposed that granite, gneiss, schist, porphyry, 
phonolite, and similar rocks were chemical precipitates separated 
from a primitive ocean strongly impregnated with mineral sub- 
stances. Therefore Von Fichtel, writing in the end of the 
eighteenth century, showed an exceptionally enlightened spirit 
among German geologists when he included not only basalt 
but all granitoid, gneissose, schistose, and doleritic series as 
igneous in their origin. Fichtel distinguished two kinds of 
volcanic mountains (a) those which consist of immense 
uniform masses, sometimes building up a whole mountain- 
' chain, and (b] those in which rocks of different constitution 
alternate with one another in a stratified way (lava, ashes, 
rapilli, etc.). He described the homogeneous masses as having 
risen without any violent phenomena of eruption, and having 
penetrated the crust at the places of least resistance ; whereas 
the others were produced by successive eruptions, during which 
the ejected material gathered in conical form round the craters 
of eruption. 

But the great founder of the Plutonic school was James 
Hutton. According to Hutton, heat is the most powerful 
agent in the origin of rocks. The heat that pervades the lower 
horizons of the crust converts all rock-material into a molten 
magma. Under the superincumbent weight of the younger 
sedimentary rocks and the ocean, mineralogical combinations 
can take place which would not be possible at the surface 
under conditions of normal pressure and rapid cooling. The 
primitive schists and limestones have been produced from a 


molten mass in this way ; granite, porphyry, trap, basalt, and 
similar rocks were pressed up by subterranean heat, but did 
not reach the surface ; they were intercalated as subterranean 
eruptive masses partially between pre-existing sedimentary 
rocks, or they spread as extensive sheets of rock-magma on 
the ocean-floor. Notwithstanding the strong support given to 
Hutton's theory by his friends and adherents, Hall, Playfair, 
and Watt, the theory of the Scottish genius found little recog- 
nition in his life-time. The Plutonic doctrines were slow to 
plant their roots in geological literature, and it was not until 
the third decade of the nineteenth century that they were 
universally accepted. 

Palceontology. The first two decades of the nineteenth 
century, which were remarkable for the great advances in 
petrography, were less fruitful in the domain of palaeontology. 
In Germany, the Wernerian school was almost wholly absorbed 
in the study of rocks, and the petrified remains of plants and 
animals were in a measure neglected. The splendid work of 
Walch and Knorr had been followed by Schroter's Introduction 
to the Knowledge of Rocks and Fossils, the value of which rested 
chiefly upon its bibliographical merits (1774-84). 

The famous Gottingen zoologist, Blumenbach, published in 
1803 and 1816 two short treatises on fossils. He sub-divided 
fossils into four groups: (i) Fossils identical with existing 
species still represented in the same localities where the fossil 
forms existed ; (2) fossils identical with existing species, but 
not with those at present inhabiting the particular localities 
where the fossils occur; (3) fossils indicative of some great 
climatic change in the localities where they are found e.g., 
cave-lion, rhinoceros, etc., which resemble but are not identical 
with living species ; (4) marine fossils belonging to extinct 
species, and showing that the earth was once covered by the 

It seems surprising that such crude and superficial concep- 
tions of fossil groups should have been formulated by a 
zoologist of the reputation of Blumenbach, yet such was his 
fame that his opinions received far more attention than they 

Baron Ernst von Schlotheim (1764-1832) was one of the few 
adherents of Werner who devoted himself to the study of 
fossils. His first work, published at Gotha in 1804, was a 


monograph of the plant impressions in the Carboniferous forma- 
tion on the Thuringian districts, and was quite the best work 
on fossil plants that had appeared. Schlotheim concluded 
that, in spite of the resemblance between the tree-ferns of the 
Carboniferous formation and certain East Indian and American 
ferns, the fossil types belonged to extinct genera and species. 
The same was, he said, true for the other forms of Carbon- 
iferous plants, and it was possible that the fossil flora of the 
Carboniferous epoch represented a wholly extinct plant-world. 
Schlotheim left it an open question whether, in this case, the fossil 
genera had died out, or whether their descendants had become 
so much modified that they could scarcely be recognised as 

Schlotheim's later work, his Petrefaktenkunde^ published in 
1820, enumerated and described the fossil specimens in his 
private collection. At the same time, in its plan it formed a 
continuation of his previous work, and the fifteen quarto plates 
of the Carboniferous flora were incorporated, together with 
twenty-two new plates, to illustrate the larger work. The 
plates were admirably carried out, and the specimens, which 
included all types of animal life, were for the first time in 
Germany named according to the binomial nomenclature. 
Hence the work has had a permanent value in literature, 
although it is true the descriptive text is often insufficient, and 
a species can be ^identified only by comparison with Schlot- 
heim's originals, which have been preserved in the Berlin 

Faujas de Saint-Fond's works on fossil organisms can scarcely 
be compared with those of Schlotheim. The first volume of 
his Essay on Geology (Paris, 1803) is devoted almost exclu- 
sively to fossils. But he held the narrow, antiquated opinion 
that the great majority of fossil forms represented existing 
species of plants and animals, while the few forms for which 
no living analogues were forthcoming probably belonged to 
species now living in unexplored portions of the globe. 

Defrance was one of the most industrious and careful of the 
early palaeontographical annotators. In his Sketch of Fossil 
Organisms (Paris, 1824) he gave a short account of all known 
fossils, with accurate mention of their localities and state of 
preservation. Between 1816 and 1830 he contributed to the 
Dictionary of Natural Science numerous treatises on fossil 
foraminifers, corals, molluscs, annelids, and echinids. 


In England, with the exception of Woodward's " Catalogue " 
of the collection now preserved in Cambridge, there was no 
general work on fossils. James Parkinson tried to supply this 
deficiency in his work, Organic Remains of a Former World 
(1804-11); the epistolary style was selected as the most easy 
of comprehension, and the most likely to stimulate popular 
interest in fossils. The first volume gave in forty-eight letters 
a short history of palaeontological knowledge, an account of the 
various views about fossils or " Medals of Creation " (a name 
which Parkinson and others had adopted from Bergman), 
and a discussion of the surface forms and physical constitution 
of the earth. Peat, lignite, brown-coal and coal, buried woods, 
bitumen, etc., were then described according to their pro- 
perties, their mode of occurrence, state of preservation, and 
the changes they had passed through. The various fossil 
woods, leaf-impressions, ferns, stems, branches, and fruits 
belonging chiefly to Carboniferous and Tertiary times were 
enumerated and compared with existing types; nine coloured 
quarto plates complete this volume. 

Parkinson shared in great measure the older conceptions of 
the " diluvialists " about the origin of fossils; the comparison 
of fossil and living forms, which he carried out in collaboration 
with the botanist, J. Edward Smith, led him to the conclusion 
that the most of the fossil plant types were the products of a 
warmer climate. Parkinson unfortunately made no attempt to 
identify the fossil plants according to genus and species, nor 
did he use the Linnsean method of nomenclature. Hence his 
work on fossil plants is distinctly behind the almost con- 
temporaneous publication of Schlotheim. 

The second volume treats of corals, sponges, and crinoids, 
and comprises twenty-nine letters and nineteen plates. The 
Linnaean method of nomenclature was introduced into this 
volume, but was not carried uniformly through the work. 
In the third volume, with 22 plates, Parkinson had the 
advantage of fuller reference literature. He could refer to the 
works of Klein and Leske on Echinoderms, to the writings of 
Lamarck on Molluscs, to the result of Cuvier's investigations 
on Vertebrates. We find the author's views considerably 
expanded in this volume, wherein he becomes more and more 
convinced that numerous fossil species belonged to extinct 
forms of life. Moreover, the influence of William Smith's 
researches had spread amongst English geologists, and taught 


them the chronological succession of the strata. Parkinson 
finally expressed his belief that the Mosaic account of Creation 
could only be accepted in its general intent, that the "days" 
of the Biblical account in reality indicated very long periods of 
time in the development of the earth. A summary of Parkin- 
son's work was afterwards published under the title of Outline 
of Oryctology (London, 1822). 

While these were the more representative, works on palaeon- 
tology which appeared in Germany, France, and England 
during the early decades of last century, numerous papers on 
special fossil genera or local faunas were published in scientific 
memoirs and journals. A few of the more important works 
devoted to the various animal types may be mentioned. 

In the class of Protozoa, fossil Nummulites had been known 
to the ancients. Herodotus had mentioned their occurrence 
in Egypt, and Strabo had compared them with lentils. Conrad 
Gesner (1565) described the first Nummulites known in 
Europe; they were found in the neighbourhood of Paris, and 
referred to the Ammonites. Aldrovandi regarded them as 
sports of nature, and Kircher described them under the name 
of "caraway" or "cummin" stones. Good descriptions and 
illustrations of Swiss Nummulites were given by Scheuchzer 
and Lang, and after that time they were included in all 
collective works on fossils under various names discoliths, 
helmintholites, helicites, nummulites, lenticulites. Special 
papers were written upon them, but authors failed to arrive at 
any clear understanding about their zoological position. As a 
rule they were associated with Nautilus and the Ammonites, but 
they were sometimes regarded as worms (De Saussure), or as 
the inner shells of molluscs (Fortis, De Luc). 

In 1711 J. B. Beccari discovered the first small fossil 
forami/iifers in the Tertiary sand of Bologna, and compared 
them later (1731) with the small shells found by Janus Planchus 
(Bianchi) on the beach of Rimini. In 1791 Soldani published 
his excellent work on the foraminifers from the Tertiary strata 
of Siena; the figures show the specimens many times enlarged. 
Fichtel and Moll prepared a monograph, with twenty-four 
coloured plates, showing all foraminifers known up to 1803, the 
date of publication, and Batsch gave a number of clear illustra- 
tions of different genera and species. Nothing was known about 
the soft parts of the foraminifers; the whole literature confined 
itself to the description and classification of the shells. 


Good illustrations of sponges appeared in the pictorial works 
of the seventeenth and eighteenth centuries, but they were 
generally termed pelagic plants or fruits, or were included with 
corals and bryozoa, under such names as corallioliths, alcyonias, 

Guettard was the first to publish a more detailed investiga- 
tion of fossil sponges. His researches were not confined to 
the description of external features, but made a careful note of 
the inner construction, the canals and openings. At first 
Guettard rightly compared the fossil specimens with existing 
sponges, afterwards he placed them with corals, but ultimately 
returned to his first idea that they were sponges. His treatises 
are accompanied by good figures, and undoubtedly rank as the 
best contributions to the older literature. Parkinson included 
the fossil sponges with alcyonarians ; he gave careful descrip- 
tions and very good illustrations of a number of Cretaceous 
and Jurassic forms, but made no attempt at systematic treat- 
ment; in his later, smaller work, Parkinson compared some 
forms with sponges, others with alcyonarians, and Schlotheim 
took much the same standpoint. 

Fossil corals were figured by Knorr and Walch, and by 
most of the early writers on palaeontology. Linnaeus gave 
the Silurian coral fauna of Gothland to one of his students, 
Fougt, to be described, and Guettard published detailed works 
on fossil corals from the Dauphine and other parts of France. 
The fine illustrations of Parkinson represented more especially 
the coral types of the older strata in England and Scandinavia. 
Schlotheim also described a large number of species under the 
vague generic titles of Fungites, Porpites, Hypurites, Madre- 
porites, Milleporites, and Tubiporites. On the whole, the 
study of fossil corals was limited to external features; little was 
known about the organisation of recent corals, and the syste- 
matic arrangement had no secure basis. 

The knowledge of crinoids had reached a more favourable 
stage of advancement. The older authors in the sixteenth and 
seventeenth centuries occasionally figured the stems and crowns 
of crinoids under the terms of trochite, entrochite, encrinus, 
pentacrinus, or under such popular terms as fossil "wheels," 
"lilies," "pennies," etc. The classificatory position of fossil 
crinoid remains continued, however, quite indefinite until 
Rosinus in 1718 demonstrated their affinities with existing 
representatives of the Eiiryalecs^ an Ophiuroid family. Rosinus 



in his treatise proved conclusively that the fossil crinoid stems 
were not independent individuals, as had been erroneously 
supposed, and gave complete representations of several genera, 
more especially of the genus Encrinus. 

The first example of a living Pentacrinus came from Mar- 
tinique, and was described by Guettard, who fully recognised 
the relationship of the recent species with earlier forms in the 
Liassic and Jurassic strata. 

Schulze and Parkinson added valuable data to the investi- 
gation and relationship of sea-lilies, as the crinoids were 
commonly designated; while Blumenbach classified them in 
near relationship to the ophiuroids (brittle-stars) and asteroids 
(star-fishes). But the founder of the more scientific literature 
of crinoids was Miller of Danzig, who published in 1821 
his famous work, Natural History of the Crinoidea or lily- 
shaped Animals. Miller not only gave admirable descriptions 
of a number of previously unknown species from the Carbon- 
iferous limestones of Ireland and the Upper Silurian limestones 
of Dudley, but also proposed a clear terminology for the 
individual parts of the calyx, the arms, and the stem or 

In the case of the important class Echinoidea (Sea-Urchins), 
contributions to the literature of fossil and existing forms 
practically kept pace with one another. The first systematic 
treatment of the Echinoidea was published as early as 1732 by 
John Philip Breyn of Danzig. In his work all known living 
and fossil forms were grouped under seven genera. Two years 
later Klein's Dispositio Echinodermatum appeared, and Leske 
in 1778 prepared a second and enlarged edition of this impor- 
tant work. The Klein-Leske classification recognised twenty 
genera, the names of which have only been partially continued 
in the literature. The works of Breyn and Klein have both 
sustained their reputation in zoological and palaeontological 

Fossil molluscs were always awarded a large amount of 
attention owing to the remarkable number of species, the wide 
range of distribution and favourable preservation of the shells. 
Fossil cephalopods were figured in the older works of the 
seventeenth and eighteenth centuries, as a rule under the 
names of belemnites, nautilites, ammonites, and orthoceratites. 
The Gastropods or Snails were sub-divided into numerous 
genera of somewhat indefinite characters e.g.^ Dentalites, 


Patellites, Volutites, and others; the Mussels or Conchifera 
with which Brachiopoda and Cirripedia used to be included, 
were grouped under various generic names e.g., Myacites, 
Tellinites, Pectinites, Gryphites, etc. Brachiopods were termed 
"conchse anomiae " or "Anomites," following the precedent of 
Fabio Colonna. 

The Systematic Conchology of Denis de Montfort (i 808-10) 
contained several new genera, chiefly of cephalopods, but the 
descriptions were extremely meagre. The more meritorious 
work of Bruguieres, in the Encyclopedic Methodique^ on 
living and fossil molluscs and brachiopods, was unfortunately 
cut short by the premature death of the author. 

Lamarck 1 was the great reformer and founder ot scientific 
conchology. He published in the Annales du Museum a 
monograph of the Tertiary mollusca of the Paris basin, with a 
good series of plates ; and in his Natural History of Inverte- 
brate Animals he defined the numerous genera and species of 
invertebrate animals with masterly skill and precision, and laid 
down, more especially for mollusca, a systematic basis which 
held its place for several decades. 

Another work, almost as important for the knowledge of 
fossil mollusca, although of far less scientific depth than 
Lamarck's, was the Mmeral Conchology of Great Britain, 
begun by James Sowerby in the year 1812, and completed by 
his son, James de Carle Sowerby, between 1822 and 1845. 
It is an illustrated catalogue of all the fossil mollusca occur- 

1 Jean Baptiste de Monet, Chevalier de Lamarck, born 1744 at Buz- 
antin, near Bapaume (Somme), distinguished himself early in the army 
career which he had chosen, but was wounded and had to take up another 
calling ; he then studied medicine, working in a bank to provide a means 
of livelihood, and devoted himself with enthusiasm to botany, physics, and 
chemistry. In 1773 h fi published a French Flora, in 1778 was appointed 
Custodian of the Botanical Gardens, and when he was in his fiftieth year 
was elected to the Professorship of Zoology in the Museum, an appoint- 
ment which he held until his death in 1829. In 1801 he published his 
System of Invertebrates, and between the years 1815-22 his greatest work, 
the Natural History of Invertebrate Animals. A second edition of this | 
work appeared in 1836, with additions by Deshayes and Milne-Edwards. 
In his Philosophy of Zoology, Lamarck gave all the weight of his know- 
ledge and experience to the support and elucidation of the Theory of 
Descent and Specific Variation. As is well known, Lamarck held that 
acquired characters could be transmitted to descendants, and become per- 
manently established in the race. These ideas met at first with great 
opposition, and only received support in more recent years. His ad- 
herents at the present day form the so-called Neo-Lamarckian school. 


ring in Great Britain. The six volumes appeared in parts, 
and comprise 604 cleverly-drawn coloured plates with ex- 
planatory text. The material is not arranged in any systematic 
order, the descriptions and figures have clearly been prepared 
in the succession in which the specimens came into the 
hands of the authors. A work of this character could not 
have a very high scientific value, yet both the Sowerbys 
were indefatigable collectors, good conchologists, and expert 
draughtsmen, and their work did much to advance the study 
of fossils. 

Among the monographs that appeared about this time, one 
of the best was J. C. M. Reinecke's Monograph of the 
Ammonites occurring in Coburg and Franconia (1818), a work 
describing and figuring forty species of cephatopods from the 
Jurassic and Triassic limestones of that area. Another valu- 
able local work was that of Brocchi on the Tertiary mollusca 
of Italy, Conchyliologia fossile subapennina (Milan, 1811). 

Very little was known about fossil Arthropods up to the 
year 1820. Fossil crabs had been found in the lithographic 
shales of Bavaria and the Tertiary strata of Upper Italy and 
Tranquebar; trilobites had been found in England, Sweden, 
and Bohemia, and occasionally insects had been recognised 
and figured in the older palseontological works. But no 
thorough scientific investigation of any group of arthropods 
had been undertaken. 

Fossil Fishes play a not unimportant role in the history of 
geology and palaeontology. The teeth of sharks had led 
Palissy and Steno to correct conceptions about the significance 
of fossils, and the early observations on fossil teeth were 
incorporated in all great works on the rocks. Most of the 
names given to them were fanciful e.g., "serpents' tongues," 
"birds' tongues," "swallow stones"; of the more learned 
terms, "glossopetra" and "lamiodonta" were the most usual. 

Impressions and skeletons of fishes were sometimes found 
in an excellent state of preservation in the copper slate of the 
Mansfeld district, in the Jurassic shales of Solenhofen and 
Eichstatt, the calcareous marls of Oeningen, the black slates 
of Glarus, the Tertiary calcareous shales of Monte Bolca, and 
in other localities. Volta published in 1796 a splendidly 
illustrated monograph of the fossil fishes of Monte Bolca. 
Faujas de Saint-Fond, in his Essay on Geology, and later 
Blainville in his Dictionary of Natural History (1818), gave a 


summary of the known species of fossil fishes and the localities 
in which they occurred. 

Few specimens of Amphibians had been discovered ; the 
famous " Andrias " of Scheuchzer and a few remains of frogs 
in the Oeningen beds were almost the only representatives 
known in the literature. 

Reptiles also were only known by rare specimens. Ichthy- 
osaurian vertebrae from the Liassic strata of England and 
Altdorf had been figured by Lhuyd and Baier as fish vertebrae, 
whereas Scheuchzer had taken similar specimens from Altdorf 
for human vertebrae. Sir Everard Home gave the first de- 
scription of an ichthyosaurian skull from the Lias of Lyme- 
Regis under the name of Proterosaurus (Philos. Trans., 1814). 

One of the most ancient reptiles, the Triassic Proterosaurus 
from the copper slate of Suhl, had been found as early as 
1706, and in 1710 had been assigned to the group of croco- 
diles; a second specimen was again described in 1718 by 
Linck as a crocodile, but Kundman thought it bore a stronger 
resemblance to lizards, and this was the view afterwards con- 
firmed by Cuvier. 

True crocodile remains were mentioned by Collini from the 
Liassic strata of Altdorf, and by Faujas de Saint-Fond from 
the Upper Jura of Honfleur and Le Havre and the Tertiary 
rocks of the Vicentine. In the Upper Lias of Whitby a full 
crocodile skeleton (Teleosaurus) from five to six feet long was 
seen by Chapman and Wooller, but only a few of the vertebrae 
could be saved entire (Philos. Trans., vol. 50). 

The discovery of a Mosasaurus skull in the Cretaceous tuffs 
of Petersberg, near Maestricht, has already been mentioned, 
and its identification by Cuvier as a lizard (ante, p. 107). 

A great sensation was produced when, in the Jurassic shales 
of Solenhofen, a complete skeleton of a perfectly preserved 
small saurian was found with wing-like appendages. Collini 
described and figured it as an unknown marine animal of 
doubtful zoological affinities. Blumenbach regarded it as a 
water-fowl, but Cuvier recognised the skeleton as essentially 
reptilian in structure, called it Pterodactylus, and described it 
as a flying reptile. Although Cuvier had given convincing data 
for this conclusion (in his Researches on Fossil Bones, vol. iv., 
1812), Hermann and Sommerring explained the skeleton as 
that of a mammalian genus allied to the bats. The original 
specimen is now in Munich Museum. 


All known fossil reptile forms were included by Cuvier in 
I his Researches, and were fully discussed by him in respect of 
their own characteristic features, and their affinities to living 

Among fossil Mammalia the teeth and bones of elephants 
first attracted attention and gave occasion to various hypo- 
theses. Fossil ivory and large bones were known to the 
Greeks and Romans; Suetonius reported on fossil "giant 
bones " in the Museum of Emperor Augustus at Capri, which 
probably were remains of fossil elephants. Kircher and many 
other authors in the Middle Ages mentioned the occurrence of 
elephant remains in different parts of Italy. A whole skeleton 
was unearthed at Crussol in the Rhone Valley in 1456, and a 
second in the Dauphine in 1613. The latter won great 
notoriety. A surgeon, Mazurier, said it was the skeleton of 
Teutobochus, King of the Cimbers, and made money by the 
display of individual bones in Paris and other cities. It then 
became the subject of a heated controversy between Habicot 
and Riolan \ Habicot holding the bones to be those of a man, 
Riolan asserting the bones were those of an elephant. As 
time went on, frequent discoveries of large bones were made 
in France, Belgium, and Germany. 

The skeleton found at Burgtonna in 1696 was one of the 
most famous discoveries, as it gave rise to a dispute between 
Ernst Tentzel and the medical faculty in Gotha. The 
other professors saw in the large 'bones only sports of nature, 
but Tentzel proved to their discomfiture that the bones were 
real, and had belonged to elephants. In 1700 a bed of fossil 
bones was observed near Cannstatt, containing astonishing 
numbers of elephants' teeth, some of which have been pre- 
served in the Stuttgart Museum. Pallas had made known the 
occurrences of mammoth bones in Russia and Siberia; and in 
^1796, Cuvier summarised all the previous literature on this 
ftubject in a brilliant treatise on fossil elephants. Blumen- 
bach was the first author who distinguished the fossil elephant 
or " Mammoth" under the term Elephas primigenius. from the 
two existing species. 

Another fossil mammal which received considerable atten- 
tion was the woolly-haired Rhinoceros antiquitatis or tichori- 
num. Pallas had in 1772 described a completely preserved 
carcass with hide and flesh in the frozen ground of Siberia. 
Skulls and other remains of this species were also found in 


the Rhine Valley. Faujas de Saint-Fond tried to prove, in 
opposition to Cuvier and Blumenbach, that these were identi- 
cal with the bones of species still existing in Africa. 

The Franconian caves were examined by Esper and Rosen- 
miiller, and the mammalian remains found in them were 
thoroughly investigated. The remains of Mastodon and 
Megalonyx, as well as other gigantic mammalia of America, 
were quite well known to Buffon and several writers in the 
eighteenth century. 

But almost all publications on fossil mammalia had been 
founded on a very insecure scientific basis, and had not 
attained to any satisfactory result regarding the affinities of the 
fossil to the living forms. It was the creative genius of Cuvier 1 
that erected Comparative Anatomy into an independent science, 
and denned principles upon which the investigation of fossil 
Vertebrates could be carried out with accuracy. 

Cuvier's papers on fossil Vertebrates, which originally 
appeared in the Annales du Museum, were collected in 1812 
and compiled into a separate work, the papers being arranged 
merely in the order of their publication. 

Cuvier's Researches on Fossil Bones was published as a four- 
volume work. The first volume contains the famous " Pre- 
liminary Discourse," which was really written later than the 
contents of the other three volumes, although all were published 
together in 1812. The "Discourse" was frequently altered by 
the author, and ran through six editions. It will be more fully 
discussed below. The second volume of the Researches begins 
with some remarks on the sub-divisions of the Pachydermes 
(Cuvier) among Ungttlates, and on the deposits in which their 
fossil remains occur. The account of the Pachydermes is 
followed by a series of studies on the comparative osteology of 
Hyrax, the fossil and recent walruses, hippopotami, tapirs, 
and elephants, also the extinct genus Mastodon. The text 

1 Leop. Chr. Friedr. Dagobert Georges Cuvier, born on the 24th 
August 1769 in the town of Mompelgardt (Montbeliard), which then 
belonged to Wiirtemberg, was educated at Stuttgart in the " Karl Schule." 
In 1788 he became tutor to Count d'Hericy at Fiquainville (Calvados); in 
! 795> Professor at the Central School in Paris; in 1800, Professor of 
Natural History at the College of France; in 1802, Professor of Anatomy 
at the Botanical Garden. Honours were richly showered on him: in 1814 
he was made a Councillor of State; in 1819, Chief of a Department in the 
Home Office with the title of Baron; and in 1831 a Peer of France. He 
died on the I3th May 1832. 


gives clear indication of the constructive methods adopted by 
the great anatomist. We follow him in his attempts to identify 
the remains of fossil mammalia by comparison with existing 
mammalian species, and we realise with him the necessity of a 
thorough examination of the bony skeleton of existing mam- 
mals before such a comparison can be effected. Cuvier's style 
is clear and concise, and he has the gift of vivid description. 

Eleven fossil species from the Pleistocene deposits of Europe, 
Asia, and North America are described in the second volume : 
a rhinoceros, two hippopotami, two tapirs, an elephant, and 
five mastodons. With the exception of the mastodons, all the 
species belong to genera which still exist in the tropics, 
but the geographical distribution of the Tertiary and the 
present species is very different. There may be a doubt in 
the case of the larger hippopotamus species (Hippopotamus 
major) whether the fossil and the present forms are 
specifically distinct, but in the other cases there can be no 
doubt that the forms belong to extinct species. 

Cuvier makes these points clear, and proceeds to show that 

from the condition of the bones they cannot have been 

v transported from any great distance, but that the animals must 

! tiave lived in the localities where their bones are found. Hence 

1 jhese remains afford proof that the temperate zones were, in 

the period immediately antecedent to the present, inhabited 

by a terrestrial fauna whose nearest allies are now confined to 

tropical climates. 

The third volume contains chiefly the description of the 
vertebrate remains which occur in Upper Eocene gypsiferous 
marls, in the vicinity of Paris. One or two fossil skeletons 
were found entire, and most of these remains found in the 
Paris gypsum beds were in a good state of preservation. But 
in many localities the mammalian remains occurred in poor 
preservation, and were irregularly distributed as confused 
heaps, or beds of bone fragments. It was in arranging such 
ill-assorted accumulations of bones belonging to different 
epochs that Cuvier achieved his most astonishing successes, 
and verified his laws of the correlation of parts. The in- 
vestigation of certain scattered remains of very frequent 
occurrence led him to the determination of two extinct genera, 
Palczotherium and Anoplotherium. After he had ascertained 
the skull and teeth, Cuvier kept constantly comparing the 
other bones with those of existing genera tapir, rhinoceros, 


horse and camel, and was finally able to restore the skeletons 
of these extinct genera. Then it became evident that both 
genera had comprised several species, and gradually the 
fossil remains of other genera intimately allied to these were 
discovered in the Middle and Upper Eocene strata at Issel 
(Aude), Buchsweiler (Alsace), and in the Upper Eocene 
marls in various localities. In the same way as he had 
investigated the Ungulata, Cuvier also investigated fossil 
remains belonging to Carnivora, and determined their 
relationship with living representatives. 

Cuvier was wholly convinced of the unerring accuracy of 
his comparative methods. It is told of him that on one 
occasion when a fossil skeleton came into sight in the Paris 
gypsum layers, he at once declared it to belong to the genus r> 
Didelphys, an American opossum. A number of his colleagues ( 
were sceptical of this, and in order to prove it, Cuvier indicated j 
the exact place where the characteristic marsupial bone on the 
pubis ought to be found in the rock, and in presence of his 
colleagues worked out the part from the surrounding rock, and 
displayed it to their astonished eyes. 

The third volume concludes with the description of a 
number of bird, reptile, and fish remains. The fourth volume 
contains treatises on the remains of horses, pigs, and 
rodents in the Pleistocene deposits and bone breccias of 
Gibraltar; on Carnivora in the bone caves of Germany and 
Hungary ; on some genera of the Edentate Order, Bradypus, 
Megalonyx, Megatherium; on Sirenia or "sea-cows"; on 
"sea-dogs" or the Phocidte family of the Carnivora; and 
finally, a survey of all known fossil reptiles. In this as in 
the other volumes, every chapter on fossil types is preceded 
by an exhaustive exposition of the structures of allied living 

In the whole literature of comparative anatomy and 
palaeontology there is scarcely any work that can rank with 
this great masterpiece of Cuvier. It passed through four 
editions, each edition containing additional chapters. The 
last (1834-36), edited by his brother Friedrich Cuvier, consists 
of ten volumes' of text and two volumes of illustrated plates. 

The "Preliminary Discourse" of the first volume later bore 
the title of " Discourse on the Revolutions of the Surface of 
the Globe," and was translated into several European languages. 
In it Cuvier gives expression to his views on the origin and 


changes of the earth, on the relations of fossils to the present 
creation, and on the whole sequence of life in the course of 
geological epochs. 

The Discourse begins with a demonstration that the surface 
of the earth has been devastated from time to time by violent 
revolutions and catastrophes. Cuvier argues that these took 
place suddenly, from the evidence of the flesh carcasses of 
mammalia in the gravels of Siberia, as well as from the 
accumulations of pebbles and debris which are present at 
certain horizons of the stratigraphical succession, and may be 
assumed to indicate epochs of violent movement in the 
former seas. Thus the development of organic life was 
frequently interrupted by fearful catastrophes, which in the 
earlier epochs extended over the whole surface of the globe, 
but latterly became limited to smaller areas. Countless living 
creatures fell victims to these catastrophes ; they vanished 
for ever, and left only "a few remains scarcely recognisable by 
the scientific investigator." 

A discussion of the natural 'forces which at the present day 
affect earth-surfaces leads Cuvier to the conclusion that these 
are not sufficient to explain the great revolutions of past 
epochs in the earth's history. The present agencies of ice 
and snow, running water and the ocean, volcanoes and 
earthquakes, together with disturbing astronomical con- 
ditions, are passed in review, for the purpose of demonstrating 
the insufficiency. Then Cuvier recalls the often ridiculous 
theories that philosophers and geologists invented in their 
endeavour to arrive at some adequate explanation of the great 
transformations of life and climate on the globe. He 
recognises the value of the mineralogical work of Saussure 
and Werner, but complains of the small share of attention 
bestowed by these geologists and their contemporaries upon 
fossils and the distribution of fossils in the rock-strata. Yet, 
in his opinion, it is the study of the fossilised remains of 
former faunas and floras which alone can give enlightenment 
about the earth's past, the number and order of its revolutions, 
and the history of creation. 

He regards the remains of four-footed animals as especially 
valuable, since in their case the question whether they 
belong to extinct or living genera and species can be more 
definitely determined than in the case of the lower animals. 
Even in the days of antiquity men knew fairly well all the kinds 


of four-footed animals on the globe, and at the present day 
there is little chance of new living species being discovered. 
Certainly the incompleteness and often poor preservation of 
the fossil remains of land mammals offered obstacles to exact 
identification. But they could be surmounted with the help 
of the laws of correlation enunicated by him, according to 
which all the individual parts of an organism stand in a 
definite morphological relationship to one another, so that one 
part could not undergo a change without a corresponding 
modification taking place in the correlated parts. 

Summarising the results of his own researches on fossil 
bones, Cuvier shows that these occur in strata of different age, ' 
that the fishes, amphibians, and reptiles existed before 
mammalia, that the extinct genera(/W^<?//#mz/#z, Anoplotherium, 
etc.) occur in older strata than the forms belonging to living 
genera, and that the few fossil forms which differ little from 
living species are restricted to the very youngest deposits in 
river alluvium, marshes, caves, etc. 

The exact investigation of fossil mammalia gives, according to 
Cuvier, no ground for the Lamarckian conception that the forms 
still existing have been produced by gradual modifications of 
the forms that had previously existed. On the contrary, 
Cuvier's conception was that specific features are constant^ and \ 
remain so even in domesticated breeds. 

Regarding the length of period during which man has ex- 
isted on the globe, Cuvier points out that no human remains 
have been found along with the latest accumulations of four- 
footed animals in Europe, Asia, and America, and that in all 
probability man did not make his appearance in those parts of 
the globe until after the last great world catastrophe. And 
although no exact determination of the time is attainable, 
Cuvier calculates from data of the rate of increase in sand- 
dunes, in the thickness of peat deposits, and river deltas, that 
the last great earth's revolution took place not more than 
5000 or 6000 years ago. Large parts of the terrestrial sur- 
faces of the globe were then submerged, and the floor of 
the former ocean was in many places upraised and re-con- 
stituted as islands and continents. Some few human beings 
who were not destroyed during this catastrophe wandered into 
the new lands and multiplied, founded colonies, erected monu- 
ments, collected facts of natural history, conceived scientific 


In conclusion, Cuvier draws attention to the rudimentary 
state of scientific knowledge regarding the Secondary rocks and 
the fossil organisms contained in them. " How glorious it 
would be if we could arrange the organised products of the 
universe in their chronological order, as we can already do 
with the more important mineral substances ! The knowledge 
of the order of successive forms of life would teach us about 
the organisation itself. The chronological succession of organ- 
ised forms, the exact determination of those types which 
appeared first, the simultaneous origin of certain species and 
their gradual decay, would perhaps teach us as much about 
the mysteries of organisation as we can possibly learn through 
experiments with living organisms.'"' 

When we at the present day pass in retrospect the contents 
of Cuvier's famous " Discourse," it is easy for us to perceive 
that the great anatomist was not familiar with the more ad- 
vanced geological thought of his own time. The works of 
William Smith "were apparently unknown to him, equally so 
the researches of Lehmann, Fichtel, and other of the best 
German stratigraphers. In the structure of mountain-systems, 
his views differ little from those of Buffon, Pallas, and Saus- 
vsure. What is new is that Cuvier demands a great number 
\of catastrophal revolutions, and he assumes that the earlier 
jpatastrophes were more widespread in their effects than the later. 

In supposing that an invasion of the sea was the immediate 
cause of the interment of mammalia in the youngest clays and 
gravels, Cuvier entirely misses the significance of the fact that 
these are for the most part of fresh-water origin. Again, his 
calculation of the age of the latest revolution and the appear- 
ance of man in the northern hemisphere betrays a geological 
standpoint as narrow as De Luc's or Kirwan's. But what was 
a far more serious disadvantage to science was that a man of 
Cuvier's anatomical insight and prescience should deny any 
genetical connection between the earlier organisms and those 
now living. Cuvier's erroneous convictions on this point 
exerted an enormous influence, and it is not too much to say 
that they retarded the progress of the evolutionary aspect of 
palaeontology for several decades. 

But Cuvier, by his teaching of the comparative methods, 
placed all-powerful tools in the hands of scientific men. His 
greatness rests upon the magnificent work that he accomplished 
in the domain of the Vertebrates, upon the scientific method 


which he founded for the identification of fossil bones, and 
upon his successful demonstration that the primeval mammals 
were not mere varieties of living forms, but belonged to | 
extinct species and genera. 

As Buffon had done twenty years earlier, Cuvier likewise, 
by his commanding personality, attracted many to the study 
of geology and palaeontology, and instilled enthusiasm into 
a large circle of his more intimrte friends and scientific 
disciples. Others had shown how important fossils were for 
j an understanding of the stratigraphical succession. But 
never before Cuvier had the significance of fossils been so 
energetically brought forward as a means of arriving at a true 
appreciation of animal skeletal structures, and of building up a 
history of the whole animal creation. Thus Cuvier largely 
contributed to the rapid progress that was made during the 
next quarter of the century in the detailed investigations of 
fossil organisms and their stratigraphical position. 

It is not surprising that Cuvier's Catastrophal Theory, 
which afforded a certain scientific basis for the Mosaic account 
of the "Flood," was received with special cordiality in 
England, for there, more than in any other country, theological 
doctrines had always affected geological conceptions. Many 
of the best known English geologists Greenough, Babbage, 
Sedgvvick, and others considered the " Flood " the latest of 
Cuvier's "World-Catastrophes." 

The most argumentative and influential member of this 
party was Professor Buckland. He published in 1823 a 
work entitled Reliquice. diluviance ; or, Observations on the 
Organic Remains contained in Caves, fissures, and Diluvial 
Gravel, and on other Phenomena attesting the action of a 
Universal Deluge. In this work Buckland showed that the 
majority of the Mammalian remains found in the caves and 
fissures belonged to the same genera and species as those 
which were found in the superficial gravels and clays. The 
latter he sub-divided into a lower or " diluvial " series and an 
upper or "alluvial" series comprising recent river and lake 
deposits. He emphasised the wide distribution of the diluvial 
deposits, and the fact that some of the animals interred in 
them belong to extinct species, others to existing species, 
and concluded that these deposits had been laid down by a 
universal deluge at no more remote date than a few thousand 
years ago. 


Text-books and Handbooks of Geognosy and Geology. The 
Text-books of Geology which appeared during the period 
between 1790 and 1820 showed an improvement on the 
speculative works of the preceding periods by their more 
matter-of-fact treatment of the subject. They may be taken 
as a standard of contemporary knowledge on geological 
subjects, and deserve special mention. 

Most of the German text-books during this period were 
simply repetitions of Werner's teaching. As a rule mineralogy 
and geognosy were combined in the larger text-books, but in a 
few cases geognosy was published separately. Voigt's Practical 
Knowledge of Mountains (Weimar, 1792) was one of the best i 
known, and it differed from Werner's teaching on several 
important points, such as the origin of basalt and the causes 
of volcanism. On this work Dietrich L. G. Karsten in great 
measure based his Mineralogical Tables (1800), which had a 
wide circulation. 

The most complete and trustworthy text-book founded 
on Werner's teaching was that by Franz Ambros Reuss 
(Leipzig, 1801-6), in which six volumes are devoted to 
mineralogy and two to geognosy. The first volume of the 
geognosy or geology begins with a short introduction on the 
compass and domain of geognosy and the method of geognostic 
study. The first chapter treats the earth as a whole in its 
relation to other bodies of the universe, and states the most 
important facts of astronomy and mathematical geography. 
A second chapter is devoted to physiographical matters, the 
present constitution of the earth's surface and atmosphere, and 
the changes wrought on the earth's surface by existing natural 
agencies. The third chapter is occupied with the solid crust, 
describes the various kinds according to their composition and 
structure, their age and origin, and gives an account of the 
hypotheses concerning the origin and development of the 
earth. The rocks are sub-divided in five "formation suites," 
according to Werner. The fourth chapter contains a very full 
description of the regional masses of rock extending through 
mountain-systems or over wide areas. These are enumerated 
in the order of the "formation suites," and a careful account 
is given of their composition and texture, stratification or 
jointing, geological age, origin and occurrence, and the fossils 
or ores contained in them. A special chapter on metalliferous 
ores concludes this work, the contents of which show that the 


Wernerian school already recognised most of the questions 
which are at present treated in text-books. 

Considerations of the earth's physiography, dynamical 
geology, petrography, geogeny, and architecture or tectonic 
structure were fairly familiar ground at the time; the great 
difference is in the teaching of the chronological succession of 
the rock formations. Modern geology gives pre-eminence to 
the accurate determination of the age of the rocks, stratum by 
stratum, according to the contained fossils ; Werner's disciples 
were satisfied with an approximate conception of the relative 
age of whole formations, and scarcely associated the study of 
historical succession of organised creatures with any geological 
interest or value. 

In France, three distinguished pupils of Werner wrote text- 
books upon the basis of his teaching Brochant de Villiers ( 1 800), 
De Bonnard (1819), and De Voisins (1819). The Treatise of 
Geognosy, published by D'Aubisson de Voisins, won wide popu- 
larity on account of its clearness and the elegance in its mode 
of treatment. Like Reuss, D'Aubisson held closely to the 
methodical arrangement of the subject introduced by Werner 
in his lectures, so that the general arrangement of these two 
text-books is very similar; but the French author took his 
illustrative examples chiefly from French geology, Reuss from 
German districts. In common with most of Werner's 
disciples, D'Aubisson de Voisins made many blunders in 
respect of the Secondary formations. He united Alpine 
limestones (Tri.-Jur.-Cret.), the limestones of the Jura chain, 
the Magnesian limestones (Permian) and Liassic limestones 
of England and the German Zechstein (Permian) in one group 
that of the Older Secondary limestones; and treated as 
Younger Secondary limestones, contemporaneous with German 
Muschelkalk, the Jurassic calcareous strata of France, the 
Forest Marble and Cornbrash, and Portland stone of England 
(Middle and Upper Jurassic), the Solenhofen lithographic 
stone (Upper Jurassic), and the fish-shales of Monte Bolca 

An important deviation from Werner's teaching was made 
by D'Aubisson in his insertion of Tertiary formations between 
the Secondary deposits and diluvial clays and gravels. 
According to D'Aubisson, the Tertiary series included the 
deposits of the Paris basin (now grouped as Eocene and 
Oligocene), so clearly elucidated by Brongniart and Cuvier ; 


the Faluns of Touraine (Miocene); the formations studied by 
Omalius d'Halloy in N.E. France, Belgium, and near Mainz 
(cf. p. 106); the London Clay of England; the sandy, marly, 
and clayey strata of the Isle of Wight, which Webster had 
recognised as contemporaneous with the deposits of the Paris 
basin ; the fossiliferous gypsiferous marls and lignite of Aix 
in Provence (Oligocene); the Oeningen shales and marls 
(Miocene); the fresh-water formations of Auvergne, Provence, 
Languedoc, Pyrenees, Spain, and Wiirtemberg (Miocene- 
Pliocene); the brown-coal and lignite in France, Germany, 
and England. 

The fossils occurring in these strata are also enumerated by 
D'Aubisson, but there is no attempt to determine a series of 
paloeontological horizons, or even the relative age of the 
Tertiary deposits present in the various localities. 

The excellent work of D'Aubisson de Voisins is the only 
one which merits the name of a text-book for teaching 

Robert Jameson, who tried to disseminate Werner's 
doctrines in Great Britain, met with less success in his 
Elements of Geognosy (1808). The works of Hutton, Playfair, 
and William Smith wielded a powerful influence, and were 
guiding British geologists with firm steps towards a right 
understanding of igneous rocks and the palaeontological 
succession of organic types. 

An Introduction to Geology^ written by Robert Bakewell in 
1813, ran rapidly through a number of editions. Although 
following Werner in the general treatment of the subject, 
Bakewell took up a neutral attitude on most contested points, 
and showed a just appreciation of Hutton's views. His work 
presented a clear statement of the leading geological features 
of England, and included many of his own observations. 
Strange to say, Bakewell was no supporter of the determina- 
tion of the age of rocks by the comparison of fossils. William 
Smith's investigations were not incorporated, and even in the 
fifth edition, published in 1838, the name of William Smith 
was never mentioned. 

Scipio Breislak's somewhat speculative and diffuse Intro- 
duzione alia Geologia (1811) was rapidly translated into both 
the French and German languages, and had a fairly wide 
circulation. It represented a quite different standpoint from 
the text-books written by disciples of Werner. Whereas the 


latter made it their chief desire to keep strictly to an account 
of known geological facts, Breislak throughout his work 
concerned himself mainly about the causes of geological 
phenomena. And the reactionary influence of Breislak's work 
proved so far healthful ; but chemistry and physics were still 
too little advanced to permit of an adequate solution of most 
geological phenomena, and ingenious as Breislak's conceptions 
were, they were seldom correct, and led him often far astray. 
The best part of the work is the third volume, in which 
Breislak gives a good account of volcanic phenomena and 
volcanic rocks in Italy, and contributes a number of valuable 
observations on gaseous explosions, volcanic ejecta, and on 
lava and basalt. 


The leaders of thought, whose activities towards the close of 
the eighteenth, and in the first twenty years of the nineteenth 
century, won for geology an acknowledged place as a scientific 
study, were almost all of them men of independent means. 
Only a limited number of the founders of geology and 
palaeontology belonged to teaching bodies. The universities 
were unwilling to countenance young and indefinite sciences, 
and only tardily incorporated them in their academical 
curricula. But when one after another of the universities 
recognised geology and palaeontology, the result could only be 
beneficial, and that rapid progress began which has continued 
uninterruptedly to the present day. 

Collections of rocks and fossils were started in all 
university towns, and laboiatories and institutes were founded 
and equipped in order that beginners in the study might have 
every assistance in their work, and that the more advanced 
students might be given every inducement to follow out 
selected lines of original research. The number of students 
steadily increased, the output of special papers became more 
voluminous, and every year the subject-matter of the collegiate 
course became more comprehensive. 

At first the universities, more especially in Germany, where 
Werner's system was the supreme precedent, placed the newer 
branches of geology and palaeontology under the care of the 



mineralogical professors, but, soon, specialisation was felt to 
be necessary, and professorships began to be founded for 
geology and palaeontology as a distinct scientific study. 

The encouragement given by the strict academical system 
of preparation and research, and the higher standard in the 
demand for accurate detail, had the effect of diminishing the 
influence of private individuals. Leopold von Buch, Charles 
Lyell, De la Beche, and Murchison are among the few leaders 
of modern geology who worked independently. 

With specialisation in geology and palaeontology, the spring- 
time of the science was over. The period was past when a 
man could mentally survey the whole field of petrographical 
knowledge, when great discoveries lay, so to speak, by the 
roadside, and only required to be observed. Instead of hasty, 
widely extended observations and broad generalisations, there 
began now the less brilliant, but more lasting, investigation of 
details. The telescope of a geological traveller surveying the 
rocks from afar was exchanged more and more for the 
microscope of a specially trained academician. The rapid 
advances made by modern geology are due to concentrated 
endeavour in the solution of problems of a definite and 
limited character, and the universities and academies have 
sedulously fostered the accomplishment of such work. 

Among German universities, Berlin has always held a 
distinguished place. Gustav Rose, Ehrenberg, and Beyrich 1 
were some of the famous teachers in Berlin University. For 
nearly sixty years Beyrich exerted a strong influence on the 
younger generations. Although without any great oratorical 
gifts, Beyrich fascinated his hearers by the carefully considered 
subject-matter of his lectures and the breadth of his know- 
ledge, while in his practical teaching in the field he provided a 
model of accuracy and completeness. Not a few of the greatest 

1 Heinrich Ernst Beyrich, born 1815 in Berlin, entered the Berlin 
University at the age of sixteen, and presented his thesis in 1837. Soon 
afterwards he was appointed an assistant in the mineralogical museum, and 
in 1857 was made director of the palaeontological collection. As a teacher 
he was first a privat docent (a university tutor), then an extra-Ordinary 
professor, and in 1865 became full Professor of Geology and Palaeontology 
in the University and in the Mining Academy. In 1848 the German 
Geological Society was founded, and Beyrich was one of its promoters. 
In 1873, when the Prussian Geological Survey was instituted, Beyrich was 
appointed co-director with Hauchecorne. He died in Berlin on Qth July 


teachers in Germany Von Richthofen, Von Koenen, Dames, 
Kayser, Eck, Credner, and others were pupils of Beyrich. 

Beyrich was also one of the most active promoters of 
the Geological Society of Germany. Since the Society was 
founded in 1848, it has combined and centralised almost all 
the geological activity throughout Germany. The seat of the 
Society is in Berlin, but the annual congresses meet each year 
in a different German town. 

Bonn rivalled Berlin for a long time as a leading centre of 
geological interests. A brilliant phalanx of geologists Roemer, 
Goldfuss, Bischof, Vom Rath, and others made Bonn a much 
favoured university in the middle of the nineteenth century. 
Ferdinand Roemer's Description of the Schist-Mountains of the 
Rhine and Goldfuss's Petrefacta Germanicz are monumental 
scientific works ; G. BischoFs famous Text-book of Chemical 
and Physical Geology opened a new and fascinating domain 
of scientific research to young minds ; and Bonn was the 
centre from which a reformation in petrographical methods 
spread over Germany. 

The pioneer labours of Sorby in his microscopic examination 
of rock structures were first appreciated in all their significance 
by Ferdinand Zirkel, who at that time taught in Bonn. 
Zirkel followed along Sorby's lines with such admirable skill 
that his researches became known in every land and gave a 
powerful impulse to the study of petrology. In Germany, work 
in this direction has been worthily continued, and Rosenbusch 
and his school have applied microscopic methods more par- 
ticularly to the study of crystallography. 

Leipzig University was fortunate in having for thirty years 
(1842-73) C. Fr. Naumann as Professor of Mineralogy and 
Geology. Naumann's most important work is his Text-book of 
Geognosy, which is acknowledged to be the most complete and 
thorough compendium of this science, and for many decades 
has served as a standard book for German students. The re- 
markable success of Naumann as a teacher attracted a large 
number of mineralogical students to Leipzig, and the tradition 
has been well sustained by Naumann's successors, Hermann 
Credner and Ferdinand Zirkel. 

Heidelberg University, where Rosenbusch now teaches, has 
always enjoyed a high reputation for mineralogy and geology. 
Carl von Leonhard, the editor of the Mineralogical Tasche?i- 
buch t and the founder of the Neues Jahrbuch fur Mineralogie^ 


Geologic^ und Palceontologie , was professor at Heidelberg 
for a long period of years ; and associated with him was 
Heinrich Georg Bronn, the zoologist and palaeontologist, whose 
Lethcea geognostica is still one of the main pillars of historical 
geology and palaeontology. 

Munich University was the first in Germany to institute a 
full or "Ordinary" Professorship for Geology and Palaeontology. 
Schafhautl, appointed professor in 1843, occupied himself chiefly 
with the investigation of the Bavarian Alps, which were then 
unknown geologically. He was joined in this work, in 1851, 
by Wilhelm Giimbel, who afterwards became director of the 
Bavarian Survey. During forty years Giimbel worked inde- 
fatigably m the field and as an administrator, and no single 
individual has done more for his country's cartography and 
stratigraphy than he has done for Bavaria. His works on 
Alpine geology are known to all students of complicated 
mountain structure, and are thoroughly scientific in tone 
and treatment. It is clear that the geographical position of 
Munich, at the base of the Alps, singles it out among German 
university towns as being particularly advantageous for the study 
of mountain structure. In 1866, Karl von Zittel succeeded 
Albert Oppel as Professor of Geology and Palaeontology, and 
since that time the fossil collections have been vastly ex- 
tended. A special collection has been arranged for tutorial 
purposes, and the large state collection is considered a model 
of methodical display. 

In Tubingen, Friedrich Quenstedt taught for more than half 
a century (1837-89). One of the most versatile and original 
of German geologists and a born teacher, Quenstedt not only 
attracted numerous students, but also aroused an interest for 
geology and palaeontology amongst the agricultural classes of 
Franconia, Swabia, and Wiirtemberg. What William Smith and 
Buckland did in determining the palaeontological horizons of 
the Jurassic series in England was accomplished by Quenstedt 
in Lower Bavaria. At the present day the common people, in 
the districts where his influence extended, are many of them 
enthusiastic fossil collectors, and arrange their miniature collec- 
tions with an astonishing accuracy. One of the best-known 
disciples of Quenstedt was Oscar Fraas, who created in 
Stuttgart a local fossil collection worthy of the best traditions 
of his teacher. 

The above-mentioned are only a few of the German univer- 


sities ; there are many of the smaller universities and poly- 
technic schools whose professors have won fame both in 
scientific research and as teachers. 

In Austria and in Switzerland the majority of the more 
distinguished geologists and palaeontologists since the year 
1820 have belonged to academic circles. The famous names 
of Eduard Suess, Ferdinand von Hochstetter, and Melchior 
Neumayr are associated with Vienna. Bernhard Studer in 
Bern and Arnold Escher von der Li nth in Zurich must be 
regarded as founders of geological science, while Louis Agassiz 
and Eduard Desor in Neuchatel and Alphonse Favre in 
Geneva are names of world-wide fame. 

In comparison with Germany the teaching element is less 
equally distributed in France and England. The huge metro- 
polis in each of these countries has always been the leading 
centre of mental activities, and has dwarfed the minor centres 
throughout the country. More especially is this the case in 
France, where Paris has been the centre of all geological and 
palaeontological efforts since the days of Buffon, Cuvier, 
Lamarck, and Brongniart. The great French represen- 
tatives of these studies are connected with the Botanical 
Gardens, the Sorbonne, or the School of Mines. In the 
provincial towns geological teaching is given partly by Univer- 
sity professors, partly by private teachers, and partly by mining 
engineers. In 1830, Constant Prevost, together with Ami Boue, 
Deshayes, and Desnoyers, founded the Geological Society of 
France, which has become, by means of its publications and its 
Congresses, the most influential French organisation in geology 
and palaeontology. 

In Great Britain, a no less important position is held by the 
Geological Society of London, founded in 1807. Its publica- 
tions present a true mirror of the whole historical development 
of geology and palaeontology in Great Britain during the last 
century, and the list of the Presidents of this Society, as well 
as of the Wollaston medallists, includes the most deserving 
geologists of the country. The old universities, Oxford, Cam- 
bridge, Edinburgh, Aberdeen, and Dublin, which in the heroic 
period of geology gave some of the great founders to science, 
still maintain their reputation in geology under able professors, 
and some younger colleges, such as Birmingham, now rival the 
older schools as seats of scientific learning. In Edinburgh, 
a number of enthusiastic adherents of Hutton founded the 


Scottish Geological Society in 1834, which took the place of 
Jameson's " Wernerian Society." 

Scandinavia early distinguished itselt in geological and 
mineralogical studies : Keilhau and Kjerulf in Norway, Nor- 
denskiold, Torell, Lindstrom, Nathorst, and other Swedish 
investigators, and Forchhammer and Steenstrup in Denmark, 
contributed much to the rapid progress in the earlier decades 
of the nineteenth century. Italy suffered in its scientific 
development during the prolonged and frequent political 
disturbances, but much has been done in the latter half of the 
nineteenth century. Russia has, of late, been most energetic 
and generous in its encouragement of geological and palaeon- 
tological researches. 

The third decade of the nineteenth century saw the begin- 
ning of active geological research in North America; and at 
the present day the United States and Canada are not behind 
any European land in their scientific attainments and societies. 

In proportion as geology continued to expand its scientific 
interests, its bearing upon many important technical questions 
began to be realised. It was represented to statesmen that 
geology could give valuable indications respecting mining and 
industrial prospects, road and railway construction, agriculture, 
and forestry. A desire crept in among public bodies for 
geological maps and reports of whole countries, and not only 
of local areas specially interesting to science. Practical 
England made the beginning. In 1835, under the direction of 
De la Beche, the governmental department of the Geological 
Survey of the United Kingdom was established, and special 
branches were formed for Scotland and Ireland, and afterwards 
also for the extra-European British Colonies. 

Almost simultaneously, Dufrenoy and Elie de Beaumont 
were commissioned in France to prepare a general geological 
map of that country, and after its completion in 1841, the State 
arranged for a more detailed survey. Michel Levy now directs 
the French Survey, which is carried on chiefly by mining 
engineers. Other States gradually followed the example of 
Great Britain and France, and every cultured nation now has 
its Survey Department for the investigation of the constitution 
of the ground and the mineral products within its territories. 

The establishment of State Surveys naturally removed some 
of the work that had previously fallen to the share of Univer- 
sity professors and tutors; in not a few countries, however, the 


professors have to combine both University and Survey duties. 
The Survey Departments have always preserved a strictly 
scientific character, and while fulfilling to the utmost the 
practical and commercial purposes for which they were in the 
first instance called into existence, their systematic treatment 
of vast land areas has furnished the pure science of geology 
with a wealth of observations of inestimable value for its more 
abstruse problems. 

The progress of geological cartography brought the results of 
one State Survey into touch with those of its neighbours. So 
far as geology is concerned, the present boundaries between 
adjacent countries are merely of accidental character, even the 
present configuration of a land surface is merely an episode in 
the historical cycle of events; in the previous epoch lands now 
separated may have been the common floor of a bygone sea. 
The nature of geological and palaeontological studies necessi- 
tates a constant interchange of knowledge between the different 
countries of the globe. The geologists of the Paris basin, for 
example, must know the results of the geologists of the London 
basin, maps ought to agree, faunas ought to be compared; and 
these considerations led to the institution of International 
Geological Congresses, where geologists from all countries 
might discuss the problems of common interest to the science. 
Some of the greatest men of our time, in attending these 
Congresses, have expressed their conviction that the intellectual 
fellowship of interest renders them a humble means towards 
a very great end, whereby nations, by better acquaintance 
with each other, may become more firmly welded in political 

Geology and palaeontology give great promise for the 
twentieth century In another hundred years the whole 
surface of the earth will perhaps be so well known, that works 
on comparative topographical geology will be fully accomplished 
along the lines which Eduard Suess has so ably initiated in 
his Antlilz der Erde. If at the same time the structural and 
physical problems of the solid earth-crust continue to be 
accurately investigated in all parts of the earth, it may be 
possible to determine the actual physical sequence of events in 
the origin and development of our planet. 

Again, the palaeontologist notes with interest how the study 
of past forms of life is brought every year into closer relation 
with biological researches, and how, as faunas and floras from 


foreign parts become better known, the gaps in the pakeonto- 
logical record are shown to be less insurmountable than was at 
first supposed. On the other hand, it may be that an enriched 
knowledge of extinct organic remains and their precise distri- 
bution in the various layers of the stratigraphical succession 
throughout the globe, will enable biologists to draw more 
definite conclusions regarding the first derivation, and the 
history of the descent and development of the manifold forms 
of organic life that have peopled the earth. 



Cosmogony.- It does not come within the domain of geology 
to investigate the origin of the universe and of solar and 
planetary systems. Yet such investigations are so closely 
associated with the origin and earliest history of the earth, 
that the results attained by astronomical researches have at 
all times exerted an influence upon the views of geologists. 
Visionary speculations about the beginnings of the universe 
and the earth were much in favour during the eighteenth 
century, and almost every geological work of a general char- 
acter had an astronomical introduction. In the early part of 
the nineteenth century speculation gave place before the great 
discoveries that were being made in astronomical physics. 
The explanation given by Kant and Laplace of the origin of 
the universe and the solar system found general acceptance, 
and further speculations on cosmogony and geogeny were 
thought to be either unnecessary for the immediate purposes 
of geology as a science, or were discouraged on account of 
their tendency to be wholly theoretical. Thus there followed 
a long period during which the cosmical aspects of geology 
made little advance. 

In the year 1871, at Brunswick, Helmholtz gave expres- 
sion in a popular lecture to the current conception of the 
earth's origin, based upon the principles of Kant and Laplace: 
"Our solar system was originally a chaotic nebular ball; at the 
beginning, when the nebular mass extended as far as the path 
of the outermost planets, many millions of cubic miles could 
contain scarcely one gramme of mass. At the time when this 
nebula became separated from the nebular masses of the 
neighbouring fixed stars, it possessed a slow movement of 
rotation. The natural attraction of its parts caused the nebula 
to condense, and in proportion as it condensed, rotation must 



have become more rapid, and have tended to make it discoid. 
From time to time masses became separated at the circum- 
ference of this disc under the influence of the increasing 
centrifugal force. These masses again assumed the form of 
rotating nebular balls, and either simply condensed as 
planets, or during condensation also gave off in turn peripheral 
masses which became satellites or remained, in the case of 
Saturn, as a connected ring. In another case, the mass which 
separated at the periphery of the main nebula broke up into a 
number of nebular fragments, and gave origin to the swarm of 
small planets between Mars and Jupiter. It has been deter- 
mined more recently that this process of condensation of 
loosely composed bodies is still continuing, although in less 

A new field of research was opened for astronomy in 1859, 
when the spectroscope was discovered by Kirchhoff and 
Bunsen. It was then rendered possible to learn something 
definite about the materials composing the stars and the sun. 
By the use of the spectroscope it has been ascertained that all 
matter has essentially the same constitution throughout the 
universe, the same substances taking part in the composition 
of the earth, the sun, the fixed stars, and the planetary 

The mechanical theory of heat, together with the principle 
of conservation of energy founded by Robert Mayer and by 
Helmholtz, afforded an exact explanation of the high tempera- 
ture of self-luminous cosmical bodies, since an enormous supply 
of heat must be absorbed during the processes of condensation 
of gases and differentiation of atoms. According to Helm- 
holtz, the supply of heat which the sun has accumulated during 
its condensation is sufficient, if calculated on the basis of its 
present expenditure of heat, to have extended over an interval 
of time in the past equivalent to twenty-two million years. 
And as the sun is still in process of condensation, it may yet 
continue for many millions of years to radiate and to impart 
its animating sunshine to the planets. 

Thus, in respect of the unity of matter and the temperature 
of solar and planetary bodies, the nebular theory of Kant and 
Laplace was confirmed by spectroscopical research and by the 
mechanical theory of heat. But it encountered serious diffi- 
culty when astronomers discovered that the rotation of the 
satellites of Uranus and Neptune takes place from east to west, 


a fact of which neither Kant nor Laplace had been aware. 
Uniformity in the rotation of all the bodies in the solar system 
is the fundamental conception in the theory of Laplace ; yet 
this conception was directly contradicted by the discovery that 
the satellites of the two planets farthest from the sun rotated 
in a direction opposite to the direction of rotation of all other 
known bodies in the solar system. Other weak points in the 
theory of Laplace rendered it open to criticism. Kant had 
supposed that the atoms f primitive matter originally pos- 
sessed the property of mutual attraction and repulsion, and a 
whirling motion, and that they gradually attained a uniform 
rotatory movement, while Laplace, on the other hand, had 
assumed the rotatory movement as inherent in matter; but 
neither Kant nor Laplace had tried to offer a satisfactory 
explanation of the phenomena of rotation. Moreover, these 
physicists had not attempted to explain the incandescent state 
of certain celestial bodies ; Laplace had merely assumed that 
matter was provided with an indefinite supply of heat, without 
offering any scientific hypothesis for the origin of heat. Again, 
a further contradiction was presented to the theory of Kant 
and Laplace by the approach of comets from regions of con- 
siderable space beyond the solar system. 

Several attempts were made to replace the theory of Kant 
and Laplace by a more satisfactory one. One of these was 
Madler's hypothesis in 1846, which postulated a common 
centre for the whole universe of fixed stars, but not a central 
sun whose superiority of mass controlled the movements of 
other bodies. The movement of fixed stars was said to be 
under the direction of an ideal centre of gravity. This assump- 
tion contradicted the idea of the successive formation of rings 
and the separation of masses of matter from a central body. 
According to Madler, the ring-theory of Laplace could not 
possibly be held to apply to the numerous double stars. 

The French astronomer, Faye, brings forward some re- 
markable conceptions in his recent work, Sur I'Origine du 
Monde, published in 1896. Faye does not accept the 
existence of a central mass either in the case of the heaven of 
fixed stars, or in our solar system. He supposes that originally 
a part of the universal matter had a slow, whirling movement, 
and that neighbouring masses of matter developed a movement 
in a similar direction as a consequence of the action of gravita- 
tion and mutual attraction. Thus the myriad of heavenly 


bodies took origin, and during condensation developed heat 
and light. If a star has planets associated with it, as in the 
case of our sun, the origin of these planets is, according to 
Faye, to be traced to the original slow, whirling movement of 
some part of universal matter. 

Considerable masses of primitive matter unite in the form 
of flattened rings, originally surrounding an empty centre of 
gravitation. The rings are gradually disrupted into a number 
of rotating masses, whirling with the same direction as the 
parent ring, greater masses attract smaller, absorb them, and 
finally a spherical body is formed. The planets originate in 
this way, those planets forming first whose component rings 
are relatively nearer the centre of gravitation. Meantime, 
finely divided fragments of matter meet in the centre of such a 
system, and begin to give origin to a sun. It is impossible 
here to enter further into these new conceptions of cosmogony 
so recently advanced by Faye. 

The Sun. The first information about the physical constitu- 
tion of the sun was obtained by the use of the telescope. 

David Fabricius, the son of a pastor in East Frisia, dis- 
covered in the year 1610 movable spots on the sun, and his 
observations were confirmed a few months later by the 
Bavarian Jesuit Scheiner, by the Englishman Harriot, and 
the Italian Galilei. Fabricius explained the sun-spots as 
slaggy separations from the inner incandescent nucleus of the 
sun; Scheiner regarded them as foreign masses circulating 
round the sun ; Galilei thought them clouds occurring in the 
sun's atmosphere. 

From the variability in the position of the sun-spots Scheiner 
drew for the first time the important conclusion that the sun 

The significance of the sun-spots is still a matter of dis- 
cussion among astronomers. Herschel suggested in the early 
years of last century that the sun-spots were cavities in the 
glowing atmosphere, through which the dark body of the 
sun was visible. This suggestion found much acceptance, 
until it was disproved by the spectroscopical researches of 

Kirchhoff in 1861 showed that the white-hot sun's mass was 
surrounded by a photosphere in which numerous substances 
familiar to us in the earth's constitution were present in a 


state of vapour. Kirchhoff then suggested that clouds formed 
in the white-hot photosphere, and that these clouds became 
darker as they cooled, thus giving origin to the appearance of 

Zollner contested this hypothesis on the ground of the rela- 
tively small variation in the shape of the spots, and agreed with 
the explanation given by Fabricius. Reye and Faye regarded 
the sun-spots as a result of cyclones in the lower region of the 
sun's atmosphere. There can be no doubt that storm move- 
ments take place at the surface of the sun. This was made 
evident when Sir Norman Lockyer in 1869, and in his later 
work on Solar Physics (1873), demonstrated the presence of a 
mantle of glowing vapour from which there projected gigantic 
torch-like protuberances subject to violent movement. Lockyer 
called the outer mantle of the sun " chromosphere " on account 
of its red colour. 

All the modern theories about the constitution of the sun 
agree in assuming that it must have received an immeasurably 
great supply of heat during its condensation, and that already 
a considerable quantity has been lost by radiation. Neverthe- 
less, the sun is still in a white-hot condition, and replaces the 
loss of heat by continued condensation and by absorption of 
matter attracted from sidereal space. The spectroscopical 
researches of Kirchhoff, Secchi, Zollner, Lockyer, Young, and 
others, have demonstrated that more than half of the terrestrial 
elements are present in the composition of the sun. 

In the present position of astronomical research there is no 
precise means of determining the temperature of the sun, 
although its size and density are well known. The sun is 
more than a hundred times larger than the earth, but has only 
a quarter of the earth's density. It follows from the continuity 
of the sun's spectrum that the sun's nucleus is incandescent, 
but it is difficult to decide whether the material is in a liquid 
state, as Kirchhoff and Zollner suppose, or whether Secchi 
and Faye may be correct in supposing the nucleus to be for 
the most part gaseous, including some denser portions in a 
state of stormy movement. 

The Fixed Stars and Planets. While the sun represents 
a celestial body not yet fully consolidated, although in an 
advanced stage of condensation, the nebulae, fixed stars, and 
planets give indication of the phases of development through 


which a celestial body passes before and after its consolida- 

The differences in the colour and brightness of the fixed 
stars suggested to the early astrologists that the stars differed 
in their individual constitution. The catalogue of the 
Ptolemaic Stellar Chart classifies the stars in six groups 
according to their brilliancy. The attempt was frequently 
made by Sir William Herschel among others to erect a more 
precise system upon the basis of the intensity of the light 
radiated from the different stars, but no satisfactory result was 
obtained. The grouping of stars according to their colour 
met with more success. The early astrologists distinguished 
white, yellow, and red stars; in 1686 Mariotte observed blue 
stars for the first time; and later, in 1782, Herschel observed 
double stars displaying different colours. By means of the 
spectroscope recent researches have arrived at an explanation 
of the different brilliancy and colour of the fixed stars. 

The sun and all fixed stars have a continuous spectrum that 
is interrupted by the dark lines of the vaporous substances in 
the photosphere; the Fraunhofer lines are absent in the spectra 
of planets, or bodies which have only reflected light Angelo 
Secchi in his work on "the sun," in 1872, distinguished four 
groups according to the spectroscopical character of the stars : 
i, white and blue; 2, yellow; 3, orange-coloured and red; 
4, blood-red. 

Secchi, Vogel, and Scheiner (1890) regard the differently 
coloured stars as bodies representing different phases in the 
cooling of nebulous masses. According to their investigations, 
the white and blue stars are the brightest and hottest ; their 
temperature is so high that the gases and metallic vapours in 
their photosphere only exert a very slight absorptive power, 
and the spectra are consequently either quite simple or show 
extreme faint lines. The vast concourse of yellow stars are in 
the farthest phase of condensation, which is represented by 
the sun or central star of our system ; their spectra exhibit 
numerous and powerful dark lines, indicating the presence of 
several of the metals in addition to gases and metallic vapours. 
The spectra of the red stars display broad dark streaks indi- 
cative of metallic compounds, and it is inferred that the 
temperature in those stars must be sufficiently reduced to 
allow the metallic vapours in the atmosphere to enter into 
various chemical combinations. The spectra of some of the 


nebulae were examined in 1869 by Huggins and Miller, and 
the results indicated the presence of vapour, of water, and in 
addition an element which, unknown in the earth, has been 
determined in the sun's spectrum and termed "helium." 

Next to the red stars may be grouped the so-called new 
and variable stars, sometimes brilliantly luminous, sometimes 
growing rapidly obscure or quite vanishing from observation. 
These probably represent bodies in a far-advanced stage of 
cooling, but which, owing to collision with other bodies in the 
universe, or to internal changes, temporarily ignite, emit 
eruptions of glowing gases, and perhaps in some cases 
also eruptions of molten rock-masses. 

By mathematical calculations astronomers have determined 
that in addition to luminous stars, there must be completely 
cooled dark bodies in the vault of heaven. Thus the sidereal 
world exhibits all phases from the nebulous, incandescent, 
gaseous, and vaporous states to the cooled and solid condition. 

The further history of a cooled celestial body surrounded 
by a firm crust is displayed in the various conditions of the 
planets and satellites of our solar system, and these have 
therefore a closer interest for geology. The planets move 
round the sun in slightly elliptical paths at definite distances 
from it. Of the six planets that were known in early astrology, 
Mercury is nearest the sun in position, and has itself a diameter 
of 648 miles; Venus (diam. 1,613 miles) follows Mercury, 
then the Earth (diam. 1,719 miles), then Mars (diam. 909 
miles), Jupiter (diam. 19,000 miles), and Saturn (diam. 
16,675 miles). Herschel in 1780 discovered on the 
farther side of Saturn the planet Uranus with a diameter 
of about 8000 miles, and Leverrier in 1846 discovered, by 
mathematical calculation, the outermost planet, Neptune, with 
four and a half times the diameter of the earth. 

The paths of Mars and Jupiter are separated by a much 
greater distance from one another than the- paths of the inner 
planets. Piazzi in 1801 discovered the small planet Ceres in 
this gap, and later there have been discovered more than 400 
small planetoids or asteroids, a number which is continually 
being added to by new researches. The Earth has one 
satellite, Mars two, Jupiter five, Uranus four, Saturn eight, 
Neptune one. Saturn is also further distinguished by the 
possession of a broad ring freely suspended over the equator 
and separated into three parts. 


In comparison with the Earth, the relative density of the 
planets is as follows : 

Sun . . .0.25 
Mercury . . 1.12 



Earth . . . i.oo 
Mars . . . o 70 

Jupiter . . 0.24 

Saturn . . o. 1 3 

Uranus . * o. 1 7 

Neptune . . o. 16 

The inner planets are therefore considerably heavier and more 
firmly consolidated than the outer. 

Great advances have been made in our knowledge of the 
physical constitution of the planets by means of improved 
telescopic methods and the construction of the modern large 
telescope. Mars has always been an interesting object of 
astronomical observation. As early as 1659, Huygens 
observed white spots at both poles, and the elder Herschel 
in 1781 was able to draw a sketch of the surface of Mars, 
which was afterwards improved by Hieronymus Schroter on 
the basis of researches conducted between 1786 and 1803. 
Beer and Madler distinguished pale, white, and yellowish-red 
spots from dark greenish-blue spots, and regarded the former 
as land masses, the latter as seas. Maps of Mars were pub- 
lished by several other astronomers. The Milan astronomer, 
Schiaparelli, published in 1878 a work which added much to 
our knowledge of Mars. The dark streaks crossing the light 
spots in straight or in bent lines, opening into the dark, iron- 
grey seas, are regarded by Schiaparelli as canals, and are 
mapped with hitherto unsurpassed precision, while he confirms 
the observation that mountain-chains and solitary mountains 
are quite absent. 

The telescopic examination of the rest of the planets has so 
far brought less satisfactory results. The small planet Venus, 
next in position to the Earth, seems to be surrounded by a 
dense, cloudy atmosphere, which obscures the view of the 
actual surface of the planet ; at the same time recent observa- 
tions have demonstrated round or elliptical spots of light 
colour (perhaps continents dimly visible through the atmo- 
sphere), and these are separated from one another by dark 
ribbon-like streaks. 

Keeler in 1889, by the use of the famous refractor of the 
Lick Observatory, obtained the first information about the 
constitution of Jupiter. With this instrument two reddish 



bands are visible at both sides of the equator, and a number 
of smaller streaks run parallel to them. An elliptical red spot 
can also be seen. From these observations it would appear 
that this planet is encircled by a mantle of cloud or by floating 
layers of vapour, through which the still incandescent nucleus 
shows itself as a red spot. Saturn displays a surface similar to 
that of Jupiter ; its remarkable ring was explained by Kant as 
a vaporous mass composed of infinitely fine particles. The 
two outermost planets are too remote from the Earth to permit 
of detailed telescopic examination. 

As regards the spectra of the planets, Fraunhofer had 
determined their agreement with the sun's spectrum, and in 
more recent years the spectroscope has shown that for the 
most part the planets only reflect the sun's rays. 

If one may venture to draw conclusions from these 
observations, Mars with its thin atmosphere may probably be 
regarded as the planet most akin to the Earth. Mars, and 
possibly Venus, with its thick cloud-mantle, are the only 
planets upon which living creatures could be supposed to 
exist. Life must be impossible on Mercury on account of its 
proximity to the sun ; Jupiter and Saturn radiate light of their 
own to a certain degree, and are probably still in an incan- 
descent state. The spectra of Uranus and Neptune would 
seem to indicate a condition of incomplete consolidation, and 
the low density of these planets is an additional fact in favour 
of this hypothesis. 

The Moon. The moon is the heavenly body which has 
been examined by astronomers in greatest detail. This has 
been rendered possible by its relatively small distance from 
the earth, the absence of water or clouds, as well as by the 
absence or very slight development of an atmosphere on the 
side f the moon which is exposed to us. Although classical 
literature contains scattered observations regarding the moon's 
surface, the cartography of the moon was not attempted until 
the telescope came into use. Then Galilei and other astro- 
nomers of the seventeenth century made sketches of the 
moon's surface. In the middle of the eighteenth century 
Professor Tobias Mayer projected a topographical map of the 
moon on the basis of measurements, the precision of which 
far surpassed previous attempts. In the earlier part of this 
century several astronomers published maps and reliefs of the 



moon on various scales. The largest chart was published on 
1878 by Julius Schmidt, and with the work of this great 
astronomer the older methods of investigation may be said to 
have reached their highest point. 

A new era began with the application of photography to 
the representation of moon landscapes. Warren de la Rue in 
London, Draper and Rutherford in America, obtained photo- 
graphs of remarkable beauty. But the earlier results of 
photography were far exceeded when the astronomers of the 
Lick Observatory in California made use of their giant lens. 
The large number of landscapes obtained by this means are 
now being compiled by Weinek in Prague, and a large Atlas 
of the moon is being prepared. The English astronomers, 
Nasmyth, Carpenter, Proctor, and Neison have also contri- 
buted very greatly within the last twenty years to the know- 
ledge of the constitution of the moon. 

From all these observations it has been proved that the 
moon, unlike Mars, has no seas and canals, in short no water, 
but possesses a wonderful array of mountains. With the naked 
eye, darker-looking areas can be distinguished on the moon's 
surface. From these rise numerous conical mountains, trun- 
cated at the top and with deep craters, ring-shaped mountain- 
ramparts, and magnificent, deeply-fissured mountain-massives, 
whose summits are as high as 25,000 feet above the surround- 
ing areas. In addition to these mountain-craters and rings 
which indicate a volcanic origin, certain rents have been 
discovered by Schroter in the plains, sometimes penetrating 
the volcanic cones, and therefore clearly of subsequent origin. 
A special geological interest attaches also to the presence of 
light streaks radiating from the craters. Whilst the rents 
might readily find an explanation as fractures due to contrac- 
tion, the radially-arranged light-streaks present a difficult 
question, and some authorities incline to regard them as 
streams of lava, others again as evidences of sulphurous 

The surface conformation of the moon is by no means 
constant in character. Schmidt in 1866 confirmed the dis- 
appearance of an earlier crater, while Klein and Neison in 
1877 saw the formation of a new crater. 

The American geologist Gilbert has contested the opinion 
generally accepted at the present day, that the craters and 
ring-shaped ramparts in the moon are volcanic in their origin. 


Gilbert regards them as impressions made upon the moon by 
the collision of gigantic meteorites. 

More recently, Schmick, George Darwin, and Ebert have 
endeavoured to trace the surface conformation of the moon to 
the undulations of a magma originally in hot, flowing con- 
dition. Suess has also elucidated the present surface of the 
moon upon the basis of volcanic occurrences; he compares 
lunar surface forms with the internal seething and buoyancy of 
melted masses of mineral or metallic material, and in this way 
sets forth a genetic table of the various lunar forms. 

Meteorites and Falling Stars. Reports of stones and masses 
of iron fallen from the heavens may be traced into remote 
periods of antiquity. The oldest known account is a report in 
China in the year 644 B.C. The Phoenicians, Egyptians, and 
Greeks used to preserve meteor-stones in temples, and to do 
honour to them as visible signs sent them by their gods. 

Pliny has recounted how at y^Egos Potamos, in Thracia, in 
the year 476 B.C., a mass of iron fell, "as large as a chariot," 
and was afterwards said by Anaxagoras to have been a frag- 
ment broken from the sun. 

Avicenna mentions reports of fallen stones from Egypt and 
Persia. There seems little doubt, according to Consul von 
Laurin (1845), tnat tne sacred stone in the Kaaba of Mecca is 
a meteorite. Various accounts of meteorkes in Germany date 
from the early Middle Ages. A fall of meteorites took place 
at Ensisheim, in Alsace, on the yth November 1492, and the 
account describes how a hot mass of stone, 127 kilogrammes 
in weight, fell into a field of wheat, accompanied by violent 
noises and the appearance of fire. Emperor Maximilian I. 
commanded that the stone should be preserved in the Church 
of Ensisheim. During the French Revolution the stone was 
laken to Colmar, and was then considerably cut down, so that 
now the remnant returned to the Ensisheim church only weighs 
about 40 kilogrammes. 

A full report was also given of a shower of meteorites that 
occurred at Crema, in Italy, in 1510 or 1511. Although the 
number of reports of fallen stones increased very greatly in 
the seventeenth and eighteenth centuries, the scientific opinion 
of that time made merry over the credulity of the people who 
imagined the stones fell from the heavens. 

Stiitz, for example, who was a director of the Natural History 


Collections in Vienna, said in 1751 that such stones had 
been erroneously regarded as rarities, and should be thown 
away! Fortunately this advice was not followed. 

A Commission of French observers was entrusted with the 
investigation of a meteorite that fell at Luce, in the province 
of Maine, in September 1768. The Commission drew up a 
detailed description of the mineral constitution of the stone, 
but stated it to be a physical impossibility that the stone 
could have fallen from the heavens. 

The great Wittenberg physicist, Chladni, at last demonstrated 
the correctness of the popular idea regarding meteorites. 
He published in 1794 a classical work, On the Origin of the 
mass of iron found by Pallas in Siberia, and the explanation of 
the physical appearances associated with the falling of this and 
other similar masses. Chladni regards meteorites as fragments 
of cosmic bodies, which, while travelling through space with 
enormous rapidity, come into the neighbourhood of the earth 
and are attracted by it ; they become heated by the friction of 
the atmosphere, melt superficially, and finally break up owing 
to the development of gases and elastic fluid materials. This 
is, in its essential features, the view that is at present held by 
most authorities. 

Since the appearance of Chladni's work a great number of 
meteors have been reported, and a careful register of meteor- 
ites has been drawn up in the writings of several astronomers, 
while the best specimens have been placed in museums. 

Although it might have been supposed that the full details 
and the precise scientific basis of Chladni's work would con- 
vince all investigators, this was far from being the case. Some 
still held the opinion that meteorites were of telluric origin, 
while Laplace and Berzelius regarded them as volcanic refuse 
from the moon. Tschermak thought them fragments from 
the volcanic eruptions taking place on the earth and on other 
cosmic bodies. 

The Englishman Howard was the first to investigate the 
chemical composition of meteorites. He showed that all 
meteorites have a similar composition, and chiefly consist of 
silicic acid, magnesia, iron, nickel, and sulphuret of iron. The 
investigations of other chemists have confirmed Howard's 
results, and demonstrated the presence in smaller quantity of 
a number of additional elements. In comparison with 
terrestrial rock-material the number of ingredients is very 


limited. Quartz, orthoclase, felspar, mica, hornblende, leucite, 
nepheline, garnet, and all hydrous silicates are absent, whereas 
very few of the minerals which have been recognised in 
meteorites are not known in the earth. 

In the latter part of this century, thin sections of meteorites 
have been examined microscopically, and it has been shown 
that there is more structural difference between the terrestrial 
and meteoric rock than had been supposed from macroscopic 
examination. Meteorites are in many cases composed of 
radiating spherical bodies (chondrites) or irregular fragments ; 
the rent character, the paucity of steam vesicles, and the 
absence of liquid contents give to microscopic slides of 
meteorites an unfamiliar appearance, and seem to indicate 
that they have taken origin independently of the action of 
water and vapour. 

The classification of meteorites is a very vexed question, 
some authorities placing more value upon chemical and 
mineralogical distinctions, and others upon structural distinc- 
tions. Partsch in 1843 distinguished two main groups stone 
meteorites and iron meteorites. Reichenbach rejected these 
groups as too broad, and classified meteorites in nine 
groups according to physical character, especially the colour 
and the mineral contents. Gustav Rose, who was Professor of 
Mineralogy in Berlin University, supported the earlier classifica- 
tion of Partsch, but arranged sub-groups upon a mineralogical 
basis. Daubree, the French physicist, in 1867 distinguished 
meteorites containing iron or Siderites, from Asiderites or 
meteorites without iron, and sub-divided these again. 
Meunier accepted Daubree's main groups, but erected a 
very large number of sub-groups. In England, the meteor- 
ites represented in the Collection of the British Museum 
were arranged in three groups according to Story-Maskelyne's 
classification in 1870-71: (i) Siderites (meteoric iron), (2) 
Siderolites (meteoric stones containing iron), and (3) Aerolites 
(meteoric stones without iron). 

The study of meteorites, as Daubree remarks, touches 
several of the fundamental questions in the history of the 
universe. They are the only specimens of non-terrestrial or 
cosmic bodies which we have an opportunity of investigating, 
and which can yield an insight into the constitution of those 
masses occupying the vault of heaven. The number of 
accredited falls of meteorites does not exceed a thousand, and 


as a rule the fragments which fall are small, sometimes merely 
a dust-shower. The fact that many meteorites consist wholly 
of metallic iron (with nickel), while others contain a large 
intermixture of iron grains in a matrix of silicates, indicates 
that iron plays a greater part in the composition of the 
planetoids than in that of terrestrial rock-material, in which it 
almost always occurs in combination with oxygen or sulphur. 

In the year 1870 Nordenskiold discovered on the coast of 
the Greenland island Disko, near Ovisak, gigantic blocks of 
solid nickelic iron weighing several thousand kilogrammes. 
These were at first thought to be meteoritic, until Steenstrup 
and Daubree showed that the basaltic rocks of Disko contain 
greater and smaller inclusions of iron, which are identical with 
the great blocks in every particular. It would thus seem that 
considerable masses of iron are actually present in the interior 
of the earth, as has been assumed from the earth's specific 

Sir Norman Lockyer in a recent work, The Meteoritic 
Hypothesis (1890), has attributed a very important part to 
meteorites in cosmology. He regards all luminous cosmic 
bodies as masses which have originated from swarms of 
meteorites, or from the collision of vapours to form a cosmic 

Geogeny. During the nineteenth century speculations regard- 
ing the earth's origin followed for the most part the nebular 
theory of Kant, Herschel, and Laplace, and assumed that the 
earth, in common with all other cosmical bodies, originated by 
the condensation of some part of universal matter. It was 
raised to a glowing heat during the process of condensation, 
and after a protracted period of cooling a solid crust began to 
form on the exposed surfaces. 

This theory was further established by Fourier in 1820, and 
by Poisson in 1835. Nevertheless, the Neptunian doctrine 
which had flourished in the end of the eighteenth century, 
under the influence of Werner, was again resuscitated, and its 
adherents passed under the name of .Neo-Neptunists. The 
Munich chemist Fuchs was the leader of the Neo-Neptunists, 
and amongst his followers were Schubert, Schafhautl, and 
Andreas Wagner. Their conception of the beginning of the 
earth was literally the same as that given by the Bible, 
" In the beginning the world was empty and void." 


The Neptunist idea that the' solid materials of the earth had 
originally been held in solution by a primaeval ocean, no longer 
harmonised with the advance of chemical knowledge. Hence 
the Neo-Neptunist leader depicted the primitive earth as 
amorphous in constitution, silicic and carbonic acid having 
united all the component particles in a pasty mass. The 
formation of rock-material began with the separation of the 
silicates. Light and heat developed as crystallisation pro- 
ceeded. The earth became self-luminous, and "certain effects 
were produced which have a resemblance to volcanoes." 
Different kinds 'of rock separated from the primitive 
amorphous substance, such as granite, syenite, porphyry, 
gneiss, crystalline schists, greenstone, slates ; and afterwards 
sandstone, quartziferous sand, clay, and flint. A calcareous 
series formed contemporaneously with the siliceous rock-series, 
the calcareous rocks then becoming more strongly developed 
in proportion as the siliceous rocks were less developed. A car- 
boniferous series of rocks began with the formation of graphite 
and anthracite, reached its maximum in the Carboniferous 
period, and closed in the youngest mountain-ranges with 
brown-coal and turf. 

Although the theory of Fuchs was so fantastic that it was 
practically ignored by geologists, it had at least the merit of 
calling attention to a possible origin of granite, gneiss, schists, 
etc., in some other way than from a molten magma. Schaf- 
hautl was one of the few geologists who accepted the theory of 
the aqueous origin of crystalline rocks, as he had himself 
succeeded in producing quartz crystals artificially under the 
action of superheated water. 

Amongst the writers who supported the nebular theory, the 
French physicist Ampere was one of the most distinguished. 
In 1833 he published his " Theorie de la Terre " in the Revue 
des Deux Mondes. Ampere held the view that during the 
gradual cooling of the earth, the substances arranged them- 
selves in the succession of their melting-points. Irregularities 
in the arrangement of the materials were explained by Ampere 
as a result of chemical processes which caused a rise of 
temperature, renewed melting and eruption of masses that 
had already solidified. Ampere further supposed similar 
chemical processes to be still in progress in the interior of the 
earth, and to be the chief cause of mountain-making, volcanoes, 
and earthquakes. 


In 1834 Henry de la Beche published his admirable work 
entitled Researches in Theoretical Geology. He described the 
earth's matter as originally in a gaseous condition, condensation 
having taken place in consequence of the constant radiation of 
heat from the earth's surface. Gradually there formed round 
the inner glowing nucleus a zone composed of heavy metallic 
substances, beyond which was a region of lighter, molten 
oxides, and externally a mantle of vapours and gases. The 
zone, rich in oxygen combinations, afterwards consolidated as 
a firm crust of crystalline rocks, which protected the inner 
nucleus and prevented its complete cooling, while the outer 
vapours condensed in the form of oceans upon the solid crust 

The Cambridge physicist, W. Hopkins, in a series of papers 
(1839-42) investigated the internal constitution of the earth by 
means of mathematical calculation. Assuming that the earth 
was originally molten, then three possibilities are set forth by 
Hopkins as a result of cooling : 

1. An outer solid crust surrounds a nucleus that is still 

molten, or 

2. The earth's sphere is surrounded by a firm crust, and 

contains a solid nucleus, both separated by a zone 
of molten material, or 

3. The earth may be completely solid. 

Hopkins calculated that the solid crust of the earth had a 
thickness of about J or \ of the earth's diameter that is, at 
least one hundred and seventy-two to two hundred and fifteen 
geographical miles. A direct communication of the internal 
molten material with the surface of the earth was therefore 
impossible in Hopkins's opinion, and he concluded that the 
volcanoes must draw their molten material from reservoirs of 
moderate size within the solid crust of the earth. 

At the same time as Hopkins was following out his mathe- 
matical and physical calculations, Bischof in Bonn was making 
experiments similar to those which had previously been 
attempted by Buffon. Bischof caused large balls of basalt to 
be melted, and observed the time required for the cooling of 
the melted basalt. By the application of the results to the 
rate of cooling of the earth, Bischof calculated that the com- 
plete solidification of the earth would occupy a period of three 
hundred and fifty million years. Naturally, the application of 
results obtained upon such a small experimental scale cannot 
be relied upon in any accurate scientific sense. It was shown 


by Sir William Thomson (Lord Kelvin), in his famous paper 
"On the Secular Cooling of the Earth" (1862), that even 
mathematical methods could not lead to any definite calcula- 
tion of the age of the earth. According to Thomson and 
Tait's Handbook of Theoretical Physics, the formation of a solid 
crust took place not less than twenty million years ago, and 
not more than four hundred million years ago. Helmholtz 
calculated, upon the basis of the original temperature of the 
earth-vapour, that the age of the earth might be sixty-eight 
million years. 

In 1893, the American geologist, Clarence King, published 
a paper " On the Age of the Earth." He supposes the earth 
to have been originally molten, and now to have a solid nucleus 
and a solid crust, and a zone of molten material between crust 
and nucleus. From a number of observations and experiments, 
King concludes that the original temperature of the earth was 
not more than 2000 C., and that its age might be about twenty- 
four million years. 

A remarkable theory of the earth's constitution was presented 
by the chemist Sterry Hunt in Canada. He starts from the 
hypothesis of a homogeneous, gaseous, rotating sphere, in 
which the parts undergoing condensation seek the centre; 
there they again become heated, and are kept circulating, 
finally settling down in zones according to their density and 
forming a molten, plastic sphere. The consolidation of this 
sphere begins in the central region. Slow cooling also goes on 
at the surface of the molten mass, and chemical combinations 
are effected there owing to the pressure of atmospheric vapours. 
Gradually a crust forms permeated with water, and in its lower 
horizons more immediately affected by the internal heat of the 
earth, the inner crust is again melted and forms a plastic 
watery zone between the solid, heated nucleus and the outer 
crust. This intermediate zone is the centre of volcanic action, 
of earthquakes, and of deforming changes in the earth's crust. 

Another ingenious thinker in this subject was Robert Mallet 
(1810-81), a civil engineer in Dublin. Mallet thought that 
the cooling of the original molten sphere began at the Poles. 
Certain portions, as they solidified at the Poles, sank into the 
molten mass, but again rose to the surface at the equatorial 
regions and began to return towards the Poles, the circulation 
of rock -material being analogous with that of the ocean currents 
at the present day. The formation of a crust proceeded out- 


wards from the Poles. At first it was merely a thin, flexible 
rind on the viscous or liquid inner mass. Then the crust 
while still hot, and locally at a red glow, broke and tore ; the 
first rains collected in the depressions, and systems of tensions 
and pressures were generated in consequence of the subsidence 
of crust-blocks. A more complete phase of movement was 
reached as the crust became gradually thicker; forces which 
had during contraction been acting vertically towards the 
centre were diverted in a tangential direction by the resistance 
of the crust, and produced the folds and wrinkles represented 
in our mountain-chains. Continents and oceans also formed, 
and the crust was in a state to sustain life. In the fourth or 
final phase, to which the present belongs, the crust has become 
very thick; cooling and contraction are now proceeding very 
slowly; the tangential pressures called forth by the sinking 
crust are relieved by horizontal compression of the rocks at 
zones and localities of crust-weaknesses. The work done by 
pressure and fragmentation is converted into heat ; and it was 
by means of this transmutation that Mallet explained the 
origin of the earth's own heat, and of volcanoes. 

Mallet's explanation was warmly contested by O. Lang 
and Julius Roth. Lang differed from most physicists and 
chemists in his opinion that an increase in volume and not a 
contraction took place during the transition of the earth's 
material from the molten into the solid state. He attributed 
the origin of volcanoes to the expansion of the outer rock- 
materials during their consolidation and the necessity of 
additional space. 

Ries and Winkelmann published in 1881 a series of observa- 
tions on the solidification of melted metals. Their results 
were so far favourable to Lang's hypothesis in that they 
proved that, with the exception of cadmium and lead, nearly 
all other metals are heavier in the molten condition than in the 
solid. At the same time, Bischofs experiments are contradic- 
tory, since they prove that the most important plutonic rocks, 
such as granite, trachyte, basalt, suffer considerable contraction 
in passing from the molten into the solid state. 

Faye, whose principles of cosmogony were briefly referred to 
above (p. 155), also made an attempt to explain the origin and 
development of the earth in agreement both with the doctrines 
of modern astronomy and with those of geology and palaeon- 
tology. Starting from his own standpoint that the earth and 


Hhe inner planets were in existence before the sun, Faye 
supposes that the first traces of organic life on the earth 
originated under the diffuse light of the still unconsolidated 
sun, that a uniform climate reigned over the whole earth 
during the Primary epochs, and that consequently the distri- 
bution of plant and animal life cannot, as is frequently stated, 
have proceeded from the Poles. 



THE subject of physiographical geology coincides in essential 
features with that of geophysics (or physical geography). The 
only distinction that may be drawn is that while physical 
geography deals more with the description and exact determina- 
tion of the physical properties of the earth's body, physio 
graphical geology concerns itself more with the causes and 
effects of these relations. It is, however, impossible to define 
a strict line of division between the studies of geograph) 
and geology. 

Certain questions about the physiography of the earth hac 
been discussed by the Greek philosophers, and the knowledge 
of the ancients in this domain had in all probability beer 
comprised in a book of Theophrastus. Unfortunately the bool 
has been lost, and is known to us only through excerpts fron: 
it that appeared in the works of later geographers. 

The first work that merits the name of a physical descriptior 
of the earth is the famous Geographia Generalis of Bernharc 
Varenius (Amsterdam, 1672). In 1661 the comprehensive 
work of Riccioli, and in 1664 that of Kircher, appeared 
nearly a hundred years later followed the important geographical 
and physiographical text-books of the Dutchman Lulofs (1750} 
and the Swede Tobern Bergman (1769). Bergman's work was 
taken as a model by the famous Werner in his teaching oi 
geognosy, and thus its style and general treatment came to be 
handed down in the later text-books published by pupils oi 
Werner. All the text-books of the Wernerian school, especial!) 
those of Fr. Ambros Reuss, F. R. Richter (Freiberg, 1812)5 
and K. A. Kiihn (Freiberg, 1833), contain a full account ol 
physiographical geology. 

In France, Buache had in 1756 kept physical geograph) 



within narrower limits than his contemporaries ; on the other 
hand, Desmarest in 1795 began a very large work in the Ency- 
clopedic Methodique, in which he treated the subject in the 
wide sense more generally accepted at that time. 

No less a scientist than Immanuel Kant was the first in 

Germany to hold academical lectures on physical geography. 

1 Kant's lectures were published in text-book form at Konigs- 

,, berg in 1802. They contained nothing remarkably new, yet 

an importance attached to them as the first attempt to collect 

the subject-matter within concise and definite limits. 

In the years 1827 and 1828 Alexander von Humboldt 
delivered his famous lectures at the Berlin University and the 
; Academy of Singing. Under the inspiring influence of this 
| great geographer, Friedrich Hoffmann prepared his inter- 
esting work on physical geography (1837). Almost simul- 
' taneously, in the year 1836, Heinrich Berghaus published 
' at Gotha a Physical Atlas which contained a collection of maps 
presenting the facts of physical geography in a manner that at 
once appealed to the eye and understanding. This graphic 
treatment of the subject marked a new and successful 
i departure in geography, which was immediately imitated in 
i other countries. The excellent Physical Atlas of the Scottish 
| publisher, Keith Johnstone, is essentially an imitation of the 
j Berghaus Atlas, increased by a few special maps of Great 
' Britain, and some additions contributed by two German col- 
leagues, H. Lange and A. Petermann. The Geographical 
i Institute at Gotha kept its leading place in cartographical 
I science, and published between the years 1886 and 1892 a 
new and enlarged edition of the original atlas of Heinrich 
i Berghaus, under the editorship of his nephew, Hermann 
r Berghaus. 

The year 1845 will ever be remembered in geographical 
I science as the date of the publication of the first volume of 
I Alexander von Humboldt's great work, The Cosmos. This 
I magnificent physical description of the world gives a complete 
. account of the knowledge of natural science in all civilised 
races up to the middle of the nineteenth century. It is a more 
extensive work than had ever before been undertaken by a 
. single individual, and a work that is not likely to be attempted 
again in the future. As Peschel has said, Humboldt's Cosmos 
comprises thousands of facts, of measurements, and of cal- 
culations reckoned according to the most exact scientific 


methods which were then known ; it is an imago mnndi, or 
mirror of the world, of the most faithful kind. 

Immediately before the publication of Humboldt's Cosmos, 
in 1844, Bernhardt Studer, the Swiss geologist, published a text- 
book of physical geography and geology, which is remarkable 
for its clearness of disposition, mastery of the subject, familiarity 
with the literature, and conciseness of treatment. 

Numerous text-books of physiographical geology appeared 
in the latter half of the nineteenth century; amongst others 
may be mentioned those of Oscar Peschel (1879), f Siegmund 
Giinther (new ed., 1897-99), tne popular La Terre of Elisee 
Reclus (1868-69), those of Hann, Bruckner, and Kirchhoff, 
and the able chapters in Sir Archibald Geikie's Text-book of 
Geology (3rd ed., 1893). 

Form, Size, and Weight of the Earth. The determination 
of the form, the size, and the weight of the earth, although of 
great interest to geologists, is more especially the domain of 
the geographer, and cannot here in the narrow limits of space 
be treated with historical detail. Suffice it to state the present 
standpoint of our knowledge. For the actual form of the 
earth, with its numerous deviations from the spheroid of 
rotation, Listing proposed in 1872 the name of "Geoid," and 
it is at present one of the chief tasks of the International Com- 
mission for the measurement of the degree to arrive at the true 
form of the geoid. 

The form of the geoid, however, cannot be discovered 
merely by trigonometric methods ; probably the pendulum will 
play an important part in the future solution of the problem. 
It has already been demonstrated that the oscillations of the 
pendulum do not everywhere depend upon the distance from 
the earth's centre; it is more especially in the interior of con- 
tinents that the deviations indicate a diminution in the force 
of gravity. Faye is therefore of opinion, that in consequence 
of the stronger cooling, the earth's crust is denser under the 
floor of the ocean than under the continents. Helmert, 
Hergesell, Drygalski, and others, have supported Faye's hypo- 
thesis in its main features ; they are of opinion, however, that 
the attractive force exerted by continents on neighbouring 
ocean surfaces is more or less compensated for by the smaller 
density of the earth's crust under the continents. 

The pendulum observations made by Von Sterneck in the 


eastern Alps and Carpathians yielded results which showed as 
a rule relative " defects of mass " in the mountains, and 
"surplus of mass" in the plains, and such results suggested 
in geological circles, a correlation between crust-movements 
and conditions of density in the crust. But, since the publica- 
tion of these measurements, more recent observations taken in 
the leading European and foreign observatories, have led to the 
conclusion that there is no immediate connection between the 
density of the earth's crust and the tectonic structure of the 

Pendulum observations are even more important for the 
determination of the specific gravity of the earth than for 
questions regarding its form. According to the law of gravita- 
tion, the action of two masses is proportional to their size, and 
inversely proportional to the square root of the distance of 
their central points of attraction. Hence if a body be simul- 
taneously subjected to the attractive forces of the earth, and of 
another mass of some considerable gravity, the density of the 
earth may be calculated from the result. 

The two Scotsmen, Maskelyne and Hutton, made in the 
years 1774 to 1776 a series of admirable experiments at the 
mountain of Schiehallion, in Perthshire. Their aim was to 
arrive at the density of the earth by means of the pendulum 
deviations in the presence of the mass of Schiehallion. The 
size, form, and weight of the solitary mountain were calculated 
by trigonometry, and the local deviations of the pendulum 
were observed as the pendulum was brought into the neigh- 
bourhood of the disturbing mass of Schiehallion , the result 
was a gravity of 4.713 for the earth. Observations have since 
been taken at many different parts of the world, and various 
figures have been in later years given for the earth's gravity 
(4.39, 6.62, and 5. 77). 

All determinations of the earth's gravity agree in showing 
that the gravity of the earth as a whole is very much greater 
than the gravity of the rocky crust, which has an average 
gravity not exceeding 2.5. Thus we know the important geo- 
logical fact that the interior of the earth is neither empty nor 
can it be filled with water, but it must consist of substances of 
very great weight. 

The Earttts Internal Heat and the Constitution of its 
Interior. It has long been known that the heat of the sun 


and the atmosphere influences the temperature of the ground 
only to a limited depth below the surface. It was determined 
during the eighteenth century that external influences are 
perceptible only within depths of abou.t 30 feet, or as far 
down as 80 feet, according to the geographical position of the 
locality. At the so-called "neutral" zone, or critical horizon 
of depth, there is a constant temperature which practically 
corresponds with the average annual temperature of the par- 
ticular place. Below this zone of constant temperature, the 
temperature increases in mines, and the increase can only be 
attributed to the earth's own heat. This increase of tempera- 
ture had already been noted by Kircher and Boyle in the 
seventeenth century, but it was not until 1740 that definite 
observations were made by Gensanne in the lead-mines of 
Giromagny in the Vosges. Gensanne's result demonstrated 
an increase of i -C. for 114 feet of depth. Measurements 
were made in 1790 and 1791 in the Freiberg mines by Freies- 
leben and Alexander von Humboldt ; Lean took observations 
in the Cornwall mines, Fantonetti in Italian mines, and 
Alexander von Humboldt in South American and Mexican 
mines. All these observations were based upon the tempera- 
ture of the air in the mines. But, as it was pointed out by 
Cordier and Reich, this temperature is influenced by air 
currents, by the mining work, and by the breath of the miners 
and of animals. Cordier and Reich then placed the thermo- 
meter in the rock itself, and taking necessary precautions for 
correction of experiments, arrived at results of a more reliable 
character. Cordier reports from French mines an average 
increase of temperature of i C. for 25 metres (circa 77 feet), 
while Reich reports grades of 41.84 metres (circa 129 feet). 

Since 1828, temperature observations have been continuously 
taken in the mines of Saxony and Prussia, and these yield an 
average of i C. for 167 feet, but as the variations range from 
48 to 355 feet, it is impossible to draw any definite law. In 
England, the British Association for the Advancement of 
Science about twenty years ago appointed a special commis- 
sion for investigations of the ground temperatures, and the 
relative capacities of heat conduction shown by different 
rocks. A great number of observations have also been con- 
tributed by other lands, but as yet no definite results have 
been obtained. The ground-borings made in various countries 
have afforded a means of taking observations on the increase 


of temperature ; generally speaking, they show an increase of 
i C. in grades of about 30 to 34 metres (104 to 118 feet). 
The results yielded by borings have been confirmed by observa- 
tions in the great Alpine tunnels. 

The Italian geologist, Giordano, published in 1870 exact 
observations made in the Mont Cenis tunnel, and the German 
civil engineer, Stapff, published those in the St. Gothard tunnel 
(1877-80). In the middle of the Mont Cenis tunnel the rock 
has a temperature of 29.5 C. 

In spite of the numerous local variations in the exact rate 
of increase of temperature, there can be no doubt that the 
temperature of the ground increases so far as depths below 
the surface have yet been reached ; the probability is that at 
still greater depths still greater increase of temperature takes 
place. Hot springs in many cases rise from great depths, and 
cannot be shown to have connection with volcanoes or with 
any particular geological formation. 

Calculations have been made with respect to the probable 
rate of progression in the increase of temperature at depths 
still unattained, but the results cannot be regarded as trust- 
worthy. Thus, although all geologists agree that the rise of 
temperature in the earth's crust is due to the internal heat of 
our planet, we have not yet sufficient data to determine either 
the prevailing inner temperature or the thickness of the earth's 

At the same time, the hot springs and geysers indicate 
temperatures that reach the boiling-point in the earth's crust, 
and the wide distribution of volcanoes demonstrates still higher 
degrees of temperature in the crust. The scientific authorities 
in the first half of the nineteenth century regarded it as an 
accepted fact that the earth's nucleus was molten, and was 
surrounded by a comparatively thin crust. Humboldt and 
Elie de Beaumont valued the thickness of the earth's crust at 
40 to 50 kilometers, and this result almost agrees with the 
more recent work of the Rev. O. Fisher, who valued the thick- 
ness at 25 English miles. But the calculations made by 
various authorities differ very considerably, some calculations 
giving a result of only 14 English miles for the thickness of the 
earth's crust, others a result as great as 75 English miles. 

The great chemist, Sir Humphrey Davy, did not believe 
in the original molten condition of the earth's nucleus. He 
believed that the earth's nucleus was originally composed of 



the earthy and alkaline metals, and that its prevailing high 
temperature was due to chemical processes. Davy's explana- 
tion afterwards found favour with De la Rive and Charles Lyell. 
Volger explained the heat of the earth partially as a product of 
the pressure which the higher mountain-systems exert upon 
the regions underlying them, partially as a result of the 
chemical changes constantly going on in the earth's crust ; 
and the Ultraneptunist chemist, Mohr, in his Gcschichte <frr 
Erde (1866), explained the internal heat of the earth as a 
transmutation of the sun's energy by chemico-physical pro- 

Lichtenberg and Franklin thought that the firm earth's crust 
surrounded a half-gaseous, half-viscous mass of very great 
density. This opinion was accepted by Herbert Spencer, and 
lias since been placed upon the basis of the Mechanical 
Heat Theory by Ritter (1879) and the geographer Zopprit/ 
(1882). According to this theory, there is under the firm 
crust a zone of viscous material, then a zone of more fluid 
material ; the earth's nucleus itself, however, is said to consist 
of an outer gaseous part, in which the gases are in their normal 
condition, and an inner gaseous part, in which they are above 
the critical point. Owing to the excessive pressure, the gaseous 
material of the earth's nucleus is said to become no less dense 
than liquid or solid bodies. 

The English physicist, Hopkins, has been one of the most 
famous champions of the theory of the earth's rigidity. Seeing 
that the earth behaves as a firm mass in response to the 
attraction of other bodies in the universe, and that the 
phenomena of precession and nutation are not consistent 
with an even partially fluid or plastic condition of the earth, 
Hopkins concluded that the earth has been rendered for the 
most part solid, in consequence of the cooling and of the great 
pressure within the earth. Like Hopkins, Poisson and Ampere 
(1868) were also of opinion that the earth's nucleus could not 
be fluid, as otherwise the attraction of the moon would cause 
gigantic tidal waves to take place in the firm crust. 

The physicists, Lord Kelvin (Sir W. Thomson) and George 
Darwin, also attribute great importance to the enormous 
pressure existing in the interior of the earth, and the con- 
solidation of the nucleus from this cause. Darwin agrees 
with Hopkins in respect of the behaviour of the earth relative 
to the sun and the moon, and tries to prove by calculation that 


if the earth's nucleus were molten, phenomena similar to ebb 
and flow would be induced which could only be resisted by a 
crust of enormous thickness, circa 2000-2800 English miles 
thick. Besides, if the earth's body were plastic, the oceanic 
tides would not only be induced by the attraction of the sun 
and moon, but would also be influenced by deformations of 
the earth-spheroid. There are, however, no indications of 
this disturbing influence. Darwin therefore believes that the 
earth behaves as a rigid body and possesses probably a 
viscous-elastic constitution. 

Lord Kelvin has essentially the same opinion, and ascribes 
to the body of the earth a degree of rigidity intermediate 
between that of steel and of glass. Starting from the nebular 
theory, Lord Kelvin (1862, 1879) supposes that the cooled 
and thereby heavier masses sank inward and formed an initial 
central nucleus, which always extended towards the periphery 
as the earth's mass continued to cool, until finally almost the 
whole earth became rigid. Ries and Winkelmann contested 
(1881) this hypothesis on the ground that not only a number 
of metals, but also silicate combinations undergo a decrease 
of density at the moment when they become solid, so that 
they could not sink in a molten mass. 

The American, Barnard, wrote in 1877 a paper on the 
internal structure of the earth, considered as affecting the 
phenomena of precession and nutation. He agreed with 
Hopkins and Darwin that the behaviour of the earth under 
the attraction of other bodies in the universe shows a very 
high coefficient of rigidity for the earth's mass. Reyer in 
Vienna in the same year brought forward arguments in favour 
of the theory of rigidity, but supposed that the rigid magma 
of the nucleus was saturated and impregnated with solvents 
and gases in so great a degree, that whenever the pressure of 
the crust was relieved or modified by fractures the nuclear 
material could readily become viscous or fluid, and capable of 
eruptive action. 

In opposition to the adherents of the earth's rigidity, many 
geologists retain the older view, at least in part, in so far as 
they believe there is a zone of molten magma under the firm 
crust, and do not accept the extreme conception of the rigidity 
of the nucleus. 

Sterry Hunt advocated the view that the originally molten 
globe began to solidify in its central part. At the surface, 


great pressure was exerted by atmospheric vapours of water, 
and the molten material became saturated with these. 
Chemical processes took place, and gradually a firm crust 
formed. The lower layers of this crust came by degrees into 
the sphere of influence of the earth's own heat, and were there 
converted into a zone of " watery magma." This intermediate 
zone between the crust and the firm nucleus is, according to 
Sterry Hunt, the particular region in which plutonic and 
volcanic eruptions take origin. ("The Chemistry of the 
Primeval Earth," Geol. Mag., 1868-69.) 

Dana expressed the opinion that about two-thirds of the 
earth's mass are composed of iron, and form a rigid nucleus 
above which a viscous, hot magma forms an intermediate zone, 
while beyond that zone the earth's crust has a thickness of 
about seven or eight miles. Amongst other investigators, 
O. Fisher strongly advocated a molten viscous condition of 
the earth's nucleus upon which the firm crust rests. Within 
recent years it has become customary to apply a certain 
definite terminology to the various zones of the earth's 
spheroid, in accordance with the supposed physical condition 
of each particular zonal region. Thus Sir John Murray, in his 
Presidential Address (Geogr. Sect. Brit. Assoc., 1899), said: 
" When we regard our globe with the mind's eye, it appears at 
the present time to be formed of concentric spheres, very like, 
and still very unlike, the successive coats of an onion. Within 
is situated the vast nucleus or centrosphere ; surrounding this 
is what may be called the tektosphere (tektos, molten), a shell 
of materials in a state bordering on fusion, upon which rests 
and creeps the lithosphere. Then follow hydrosphere and 
atmosphere, with the included biosphere (bios, life). To the 
interaction of these six geospheres, through energy derived 
from internal and external sources, may be referred all the 
existing superficial phenomena of the planet." 

Recent seismological observations indicate the transmission 
of two types of waves through the earth the condensational- 
rarefactional, and the purely distortional and the study of 
these tremors supports the view that the centrosphere is 
not only solid, but possesses great uniformity of structure. 
The seismological investigations of Professors Milne and 
Knott point also to a fairly abrupt boundary or transition 
surface, where the solid nucleus passes into the somewhat 
plastic magma on which the firm upper crust rests. 


Morphology of the Earths Surface. In a general way 
Strabo, Seneca, and Ptolemy had discussed the geographical 
distribution and individual forms of the elements that make up 
the surface configuration of our globe. But the works of 
Cluverius, Nathanael Carpenter, Kircher, and Varenius in the 
seventeenth century, contain the earliest attempts at systematic 
treatment of surface forms according to their mode of origin. 
From the seventeenth century to the present day the study of 
the earth's configuration may be said to have gone hand in 
hand with that of geology, for the theories which at any time 
prevailed amongst geologists were not without influence upon 
contemporary views regarding the surface forms. 

Hutton and Playfair drew attention to the marked effects of 
water and heat upon the earth's surface ; and Werner and his 
followers showed the connection between the geological 
structure of the ground and the particular distribution of 
surface forms continents, islands, mountain-chains, solitary 
mountains, plateaux, valleys, etc. The first accurate and 
convincing proofs of the relation between geological structures 
and the shapes of mountains were given by Pallas and by De 
Saussure, who was the first to carry out the complete ascent of 
Mont Blanc. 

As our geographical knowledge widened, the necessity made 
itself felt of grouping the scattered and fragmentary facts 
together and deriving from them some general principles of 
surface morphology. An effort in this direction was made 
towards the end of the eighteenth century by Reinhold 
Forster, whose Bemerkungen auf einer Reise um die ^#(1783) 
contained a formal treatment of such features as the shape of 
the continents, the structure and position of islands, coastal 
forms, and coral reefs. 

But the ever-increasing love of travel found its first in- 
spired scientific exponent in the great Humboldt, whose 
wonderful descriptions of his personal impressions of natural 
landscapes and form were as artistic as his classification and 
distinction of structural types in tropical America and in 
Central Asia were masterly. Humboldt's writings bore essen- 
tially the stamp of an eye-witness, and were concrete in 
character. The works of Carl Ritter, his Erdkunde and books 
of travel, were abtruse and teleological, the works of a student 
and thinker. Richthofen writes of him : " Never have all the 
known facts regarding a group of geographical areas, never 


have all the researches and observations of others, been 
combined with greater completeness or with clearer philo- 
sophical conceptions than by Ritter in his monumental work 
on Asia. He has endeavoured to replace the meagre 
descriptions of his predecessors by a chorological representa- 
tion ; he has gathered information from the most varied 
sources and kneaded it into an organic and intellectual whole, 
united by the principle of causality." (The Tasks and Methods 
of Modern Geography ', Leipzig, 1883.) 

During the latter half of this century the abundance of new 
facts brought home by travellers of all nations has extended 
our knowledge with remarkable rapidity. But the treatment 
of the subject remained for a long time of the more formal 
and descriptive character. Most travellers contented them- 
selves with descriptions more or less accurate and with 
measurements, and were indifferent to the genetic aspects of 

If we except the older works, that of Humboldt may be 
said to have laid the scientific foundation of a morphological 
treatment of surface forms. His calculations of the average 
height of the great continents form the starting-point of a 
series of investigations, amongst which may be mentioned 
those of A. de Lapparent (1883), Von Tillo (1889), John 
Murray (1886), and of a number of eminent younger 
geographers. By the side of orography, oceanography has 
made even more remarkable progress during the century, and 
has developed itself into an independent branch of the 
morphology of the earth's surface. Otto gave in 1808 a fairly 
complete account of the limited facts then known about ocean 
forms. Great advances had been made when the American 
sailor Maury published his excellent work fifty years later. 
Maury gave a general idea of the extent of the ocean surfaces, 
the forms of coast-lines, the ocean tides and currents, the 
physical and chemical conditions of the water and the various 
organisms that inhabit the oceans, and was also enabled, with 
the help of three lines measured for the laying of the 
Transatlantic cables, to sketch the first section and the first 
map of the floor of the North Atlantic ocean. From these 
data Peschel in 1868 calculated the mean depth of the North 
Atlantic Ocean. 

A new era began in oceanography with the exploring 
expeditions of the English Challenger, the German Gazelle, 


and the American Tuscarora, all of which were carried out 
almost simultaneously in the years 1872-77. These were 
followed by a series of similar undertakings. 1 

The seas were investigated in all latitudes and in all zones 
by means of plumb-line soundings and deep-sea thermometer 
readings ; and the ocean sediments were brought from 
different horizons of depth by dredging-nets. In the year 
1843, Humboldt had known no greater depth than 2000 
metres. From the large number of observations taken by the 
Challenger and Tuscarora expeditions, Samuel Haughton was 
able in 1876 to calculate the mean depth of the Pacific, 
Atlantic, and Indian Oceans at 3000 to 3,650 metres. 
Kriimmel in 1878 made a most careful and accurate 
calculation from all known data, and gave the mean depth for 
all oceans at 3,438 metres. 

The old hypotheses of Athanasius Kircher, Kant, Ritter, 
and others, about submerged mountain-systems and submarine 
prolongations of continents had to give place to the newly 
obtained data. Jt was found that the greatest ocean depths 
were not in the middle of the oceans, but as a rule along the 
edge of mountainous coast-lines. The floor of the ocean has 
its different horizons of level : smooth ridges, extensive 
plateaux with gentle slopes, narrow canal-like depressions, 
connected series of deep hollows extending to depths of 6000 
metres, and even 8,500 metres below sea-level, and undulating 
crust-forms occur in all the great oceans ; but under the water 
there are no toothed mountain summits, no steep aretes, no 
valleys and ravines such as we are familiar with amongst the 
surface forms of the land produced by subaerial erosion. 

The material brought up by dredging-nets shows the nature 
of the sediments that are in course of deposition on the ocean- 
floor. "On the continental shelf, within the roo-fathom line, 
sands and gravels predominate, while on the continental slopes 
beyond the loo-fathom line, blue muds, green muds, and red 
muds, together with volcanic muds and coral muds, prevail, 
the two latter kinds of deposits being, however, more character- 
istic of the shallow water around oceanic islands. The com- 
position of all these terrigenous deposits depends on the 
structure of the adjoining land. 

1 A complete account of the expeditions which have contributed to our 
scientific knowledge of oceanography has been given up to the year 1883 in 
Boguslawsky's Handbuch der Oceanographie^ vol. i., pp. 390-400. 


" The materials composing pelagic deposits are not directly 
derived from the disintegration of the continents and other 
land-surfaces. They are largely made up of the shells and 
skeletons of marine organisms secreted in the surface-waters of 
the ocean, consisting either of carbonate of lime, such as 
pelagic Molluscs, pelagic Foraminifera, and pelagic Algae, or of 
silica, such as Diatoms and Radiolarians. The inorganic con- 
stituents of the pelagic deposits are for the most part derived 
from the attrition of floating pumice, from the disintegration 
of water-logged pumice, from showers of volcanic ashes, and 
from the debris ejected from submarine volcanoes, together 
with the products of their decomposition." (Sir John Murray, 
Brit. Assoc., 1899.) 

Throughout the earlier parts of the nineteenth century much 
labour was expended on the description of different parts of 
the continents, but the treatment was too formal to advance 
the conceptions of the connection between the physiography 
and geology of the earth. A desire gradually made itself felt, 
not only to describe, to measure, and to compare the actual 
forms and to follow their distribution, but also to explain their 
origin and development ; and the two sister studies more fully 
recognised their community of aim. The physical exposition 
of the Swiss Jura mountains by Thurmann, in 1832, gave a 
strong impulse to the new direction of thought in Europe, but 
it was in the wide plateaux of America that the first signal 
successes of physiographical geology were won. The brilliant 
works of Dana and Leslie were followed by those of Powell, 
Dutton, Gilbert, and other pioneer geologists in the Far West; 
by their vivid portrayal of the work of subaerial denudation 
the American writings roused the intellectual life of the middle 
of the century to new conceptions on a grand scale. 

' The gigantic erosion forms in the Bad Lands, the configura- 
tion of the Rocky Mountains and of the plateaux lands in 
Arizona, Colorado, and Mexico, the wonders of the Yellow- 
stone Park and California, called forth a new and rich literature, 
which demonstrated in. the most convincing way that the sur- 
face-forms of those regions are mainly the -result of the erosive 
activity of water. 

Davis, MacGee, Chamberlin, and others have worked along 
the same lines in the east of North America and the middle 
States, where ice rather than water takes the first rank as the 
agent which sculptured the prominent surface-forms. 


Independently of the Americans, the writings of Sir Andrew 
Ramsay, and of Sir Archibald Geikie and Professor James 
Geikie in Scotland, gave convincing evidence of the work of 
ice and water upon the rocks. Riitimeyer contributed in 
Switzerland a brilliant paper on the formation of valleys, while 
Desor elucidated the leading features of desert and moraine 
landscapes, and his teaching found able followers in Heim, 
Baltzer, Fellenberg, Du Pasquier, and Penck. De Lapparent 
and De Margerie in France, Torell and Helland in Scandinavia, 
Muschketow and Lewakowsky in Russia, are the leaders in this 
direction of study. 

In 1869, Oscar Peschel had collected the principles of physio- 
graphical geology into a systematic form, and thus given the 
first incentive towards converting the study of this subject into 
an independent scientific discipline. Instead of the earlier 
formal grouping of the surface- forms, the treatment of the 
subject now betokened an effort to group together all types of 
form which have a similar genetic history. What Peschel tried 
to initiate in this direction was fully realised by Baron von 
Richthofen in his book, Fuhrer jiir Forschungsreisende (Berlin, 
1886). This work, designed primarily as a guide in the 
methods of observation, is based for the most part upon the 
personal observations of the author during many years of travel 
in the Alps, Carpathians, North America, and China, and has 
become in Germany the standard work for the systematic treat- 
ment of surface-forms. 

In 1894, Penck accomplished the difficult task of arrang- 
ing our present knowledge of surface-configuration upon the 
basis of leading genetic principles. In his Morphologic der 
Erdoberfldche^ Penck has presented the chief results of the 
special literature of physiography in clear, concise form. A 
comparison of Richthofen's Fuhrer and Penck's Morphologic 
with the older works on orography and hydrography, shows 
very plainly the great improvement that has been effected by 
the new methods of study in the domain of geography. 



TN the days of the Greek philosophers attention had been 
frequently directed to the changes in the surface conformation 
of the earth, and the natural forces which produce them. 
Herodotus, Aristotle, Strabo, Seneca, Pliny, and others con- 
tributed valuable information regarding wind and weather, 
springs, water-courses, inundations, and earthquakes. A sys- 
tematic treatment of these agencies, with reference to the 
changes produced in the earth's surface, was first carried out 
by the Belgian mathematician, Simon Stevin (1548-1620). 
But it was not until two centuries later, after the physical 
investigation of the earth's surface had been conducted along 
scientific lines, and had shown the influence of these agents 
upon the existing conformation of the earth's surface, that 
geologists began to correlate the past changes in the earth's 
surface with similar natural causes. Then dynamical geology 
gradually developed as a branch of study intermediate between 
geography and geoldgy, which was fostered from both sides, 
and proved useful to geography in so far as it elucidated the 
present constitution of the earth's surface, to geology in so far 
as it served t) explain the successive phases in the earlier 

Hutton and Playfair had expressed the view that all earlier 
geological events were explicable upon the basis of the forces 
and phenomena still in action. The Scottish geologists had 
pointed out the importance of realising the high antiquity of 
our earth, and the gigantic work that might be accomplished 
by physical agencies small in themselves but acting throughout 
long periods of time. The fame and authority of the great 
Frenchmen, Buffon and Cuvier, lent support, on the other 
hand, to the conception of repeated earth catastrophes. 
Approaching the subject, as they did, from the standpoint of 

1 86 


the natural historian, rather than from the more critical stand- 
point of the physicist, chemist, or geologist, the French 
scientists and their adherents were impressed by a sense of 
the utter disproportion between the infinitesimal changes now 
taking place under the eye of man and the magnitude of the 
topographical and biological changes evinced in the remote 
past. Changes of such magnitude must, they argued, have 
been the result of stupendous revolutions in the organic and 
inorganic world, revolutions whose causes and effects were 
different both in kind and in degree from any known pheno- 
mena of the present age. 

The " Catastrophal Theory" met almost simultaneously in 
Germany, France, and England with strong opposition. In 
the year 1818 the Royal Society of Sciences in Gottingen, 
acting on a suggestion of Blumenbach's, offered a prize for the 
best " investigation of the changes that have taken place in the 
earths surface conformation since historic rimes, and the applica- 
tion which can be made of such knowledge in investigating earth 
revolutions beyond the domain of history" 

This subject was handled by Carl Ernst Adolf von Hoff with 
brilliant success. The first volume of his great work treats 
of the relation between land and sea in historic time, the 
extension of the ocean surface owing to the erosion of the 
coastal territories and invasions of the continents. The 
Volume betokens complete mastery of all the literature on 
the subject, from the authors of antiquity to the nineteenth 
century. Von Hoff proves the baselessness of the tradition of 
a buried city, Vineta, on the Pomeranian coast, and regards 
with scepticism the alleged discovery of an old map in Heligo- 
land with geographical details of this island in the ninth, 
fourteenth, and seventeenth centuries. This map was found 
afterwards to have been fabricated. The origin of the Bosphorus 
and the Strait of Gibraltar as invasions of the Black Sea and 
the Atlantic Ocean respectively is held to be probably correct 
by Von Hoff, but he disputes the occurrence of these events 
within historic time. With scholarly skill, Von Hoff proves 
that the Platonic " Atlantis " and the submerged island of 
"Friesland" can only be regarded as fables. An excellent 
description is given of the changes occasioned along the sea- 
board by the deposition of sediments, and is illustrated by 
reference to the Nile delta, the recent formations on the north 
coast of Africa, Syria and Asia Minor, the Black Sea, in the 


Greek Archipelago, in the Adriatic and Tyrrhenian Seas, on 
the north coast of the Mediterranean Sea, and on the shores of 
the Atlantic Ocean, the North and Baltic Seas. 

The second volume treats of volcanoes, earthquakes, and 
geysers. The author brings forward no new hypothesis about 
the causes of these phenomena, but follows largely the 
views of Von Humboldt and Von Buch. The chief merit 
of Von Hoff is his careful epitome of all reliable informa- 
tion regarding the changes and disturbances which have 
been produced by volcanoes and earthquakes within historic 

Ten years elapsed between the appearance of the second and 
the third volume of Von Hoff's work. During the interval 
the first volume of Charles LyelPs Principles of Geology was 
published, and its influence upon Von Hoff is quite apparent 
in the third volume of his work. In this third volume, Von 
Hoff discusses the causes of the degradation of land. The 
changes in surface conformation and the gradual destruction 
of a continent are referred to atmospheric agencies, to the 
chemical and mechanical action of water, snow, and ice, to 
living organisms, and to the erosive action and usurpations 
of the sea over coastal territories. He discredits Buckland's 
hypothesis of a universal flood in a learned and convincing 

The meritorious work of Von Hoff did not meet with the 
full recognition which it deserved. This arose largely from 
the fact that Von Hoff drew his data almost wholly from 
literature, his modest circumstances not permitting him to 
visit the localities of which he wrote; his conclusions were 
therefore based upon historical evidence. 

In France, Constant Prevost, quite independently of Von 
Hoff's work, attacked the catastrophal theory of Cuvier. In 
1825, Prevost announced his view that the physical conditions 
and phenomena of the present age were in every respect similar 
to those which had characterised the past geological epochs. 
In 1828, he repeated this opinion, and protested against 
the frequent inundations by the sea assumed by Cuvier and 
Brongniart to have taken place in the Paris basin. Prevost's 
attack upon Cuvier's theory had little effect, as it was not 
supported by any new data, and he weakened his arguments 
by allowing that certain geological forces might have developed 
stronger energies in past epochs than in the present. 


The strongest combatant who entered the lists against the 
catastrophal theory was Charles Lyell, 1 a Scotsman by birth. 
Like his two older contemporaries, Alexander von Humboldt 
and Leopold von Buch, Lyell had the good fortune to enjoy 
an independent patrimony and to be able to devote himself 
wholly to science. While he was a student in Oxford, he 
attended Buckland's lectures And showed a great interest in 
entomology. During one of his vacations he accompanied his 
parents on a three months' tour through France, Switzerland, 
and Upper Italy. It was then that Lyeli felt his enthusiasm 
aroused for geological studies. Although he completed his 
law course in the following years, he spent his leisure hours 
on geology. In 1823 he was in Paris, where he made 
the acquaintance of Cuvier, Humboldt, and Prevost, and 
afterwards made excursions with Constant Prevost in the 
West of England and in Cornwall. In the same year he 
visited Scotland in the company of Buckland. 

The manuscript of his Principles of Geology was almost 
complete in 1827, but before printing it Lyell felt the necessity 
of being able to bear personal testimony upon many points. 
Now followed a period in which he travelled to one place 
and to another, collecting a large number of new data, and 
enjoying the intercourse of the greatest geologists of his day. 
In the companionship of Murchison and his wife, Lyell in 1828 
visited Auvergne, the Velay and Vivarais, the Riviera, the 
neighbourhood of Turin, Verona, and Padua. He then con- 
tinued his journey alone to Parma, Bologna, Florence, Siena, 
Rome, Naples and Sicily, and returned home by Paris. His 
chief interest during these journeys was concentrated upon 
volcanoes and the young Tertiary formations. 

The first volume of the Principles appeared in 1830, the 
second in 1832, and the third in 1833. Meanwhile Lyell 
continued to enrich his knowledge by frequent journeys to 

1 Charles Lyell (afterwards Sir Charles Lyell, Baronet) was born at 
Kinnordy, in Forfarshire, Scotland, on the I4th November 1797, and was 
the son of a rich proprietor and the eldest of ten brothers and sisters. He 
passed his early childhood near Southampton, where his father had rented 
a country-house, attended school at Ringwood and Salisbury, studied in 
Oxford, then settled in London, and spent the rest of his life either in 
London or in travelling. He died in 1875, and was buried in West- 
minster Abbey. (T. G. Bonney, Charles Lyell and Modern Geology, Lon- 
don, 1895, and Life, Letters, and Journals of Sir Charles Lyell, Bart., 
edited by his sister-in-law, Mrs. Lyell, 2 vols., London, 1881.) 


different parts of the Continent. In 1831 he gave a course of 
lectures on geology in King's College in London. But Lyell 
would not undertake the duties of a Professor for any length 
of time. He resigned his post in order to devote himself 
exclusively to science. His wife Mary, a daughter of the 
geologist Leonard Horner, proved a devoted companion in 
all his journeys throughout their long, happy, childless mar- 
riage, and was a zealous helper to him in his work, sparing 
him many of the laborious researches that might have been 
arduous for his weak eyes. 

The publication of the Principles placed Lyell in the first 
rank of geologists, and won for him universal recognition as a 
fine observer, an acute thinker, and a master of language. The 
success of his work was unexampled. In spite of its compre- 
hensive character, six editions of it appeared between 1830 and 
1840, a seventh in the year 1847, the eighth in 1850, the ninth 
in 1853, the tenth in 1866, the eleventh in 1872, and the 
twelfth shortly after his death in 1875. Throughout the long 
space of thirty-five years between the first and last editions, 
Lyell was indefatigable in his efforts to improve the work, to 
widen his range of knowledge by his annual tours, and to test 
his opinions by intercourse with his geological colleagues. 
Lyell was as much at home in the geology of Germany, 
Belgium, France, Switzerland, and Italy as in that of Great 

In the summer of 1834 he visited Denmark and Sweden, in 
i837 1 Norway, and in 1841 he undertook his first journey to 
North America. He stayed there one year, on this occasion 
visiting chiefly Canada and the eastern part of the United 
States. He published an account of the journey in 1845, in a 
special work entitled Travels in North America. Soon after 
the publication of this volume, Lyell again crossed to America 
and investigated the southern states. The account of this 
journey appeared in another independent volume in 1849, and 
the work contained, in addition to geological observations, 
much interesting matter regarding the people and their social, 
political, and religious relations. 

In 1854, accompanied by the German geologist Hartung, 
Lyell spent several weeks in Madeira and the Canary Isles, 
where he studied the volcanoes. In his later years he re- 
visited North America twice, and went to Sicily and other 
parts of Europe, sometimes for the investigation of some 


geological question, sometimes for the sake of physical and 
mental relaxation. The Principles of Geology was published 
originally in four volumes. The first volume deals largely with 
the climatic variations in the history of the earth, and the 
influence of these upon local physical conditions and the 
nature of geological deposits. The second volume treats 
chiefly of the agencies of denudation and erosion, and com- 
prises special chapters on volcanism. The third volume 
contains a description of coral reefs, and discusses the various 
means by which organic remains may be preserved. The 
fourth volume is devoted to historical geology, and as Lyell in 
writing it adopted the results obtained in the previous volumes, 
he produced a geological text-book upon a basis which was at 
the time quite new. This volume was afterwards published 
independently under the title of Elements of Geology, and 
passed through six editions before the year 1871. 

The author's aim in the Principles is described in the 
alternative title of the work as " an inquiry how far the former 
changes of the earth's surface are referable to causes now in 
operation." After an elucidation of some leading conceptions, 
and a short but excellently written history of geology as far as 
Cuvier and Brongniart, Lyell discusses the causes of the slow 
development of his science, and the many false directions into 
which it had so often been misled. 

He shows how theological prejudices and the stubborn 
adherence to the Mosaic reckoning of time had stood in the 
way of a right appreciation of the earth's history. The 'defec- 
tive knowledge of physical phenomena now in operation on 
the floor of the ocean and in the interior of the earth had also 
served to retard the progress of knowledge respecting the 
formation of the primitive earth-crust. But in LyelPs opinion 
the greatest stumbling-block had been presented by the quite 
unphilosophical hypothesis that forces different from any 
known in the present day had been active in earlier epochs, 
and that the physical forces still existing had in the past been 
stronger in their action, and had produced effects which could 
not now be equalled. Further, the supposition that the sedi- 
mentary deposits had originally extended uniformly over the 
whole earth, as well as the catastrophal theory of sudden 
changes in the distribution of land and sea, in the climatic 
relations, and in the organic creation, had, according to Lyell, 
been hurtful to a healthy development of geology. 


The climatic variations during former periods of the earth 
were discussed by Lyell in considerable detail. He opposed 
the opinion that climatic changes had been due to the gradual 
cooling of the earth from an originally molten state, but admitted 
that during the Tertiary and Diluvial epochs there had been a 
warmer climate in Europe. During the Secondary epochs 
reef-corals had inhabited the temperate zones, and in the 
Carboniferous epoch tree-ferns and other plants indicative of a 
moist and warm climate had flourished as far north as 75 N. 
latitude. Lyell traced climatic variations to the varying dis- 
tribution of land and water, to the influence of ocean currents, 
to icebergs, and the accumulation of glacier-ice in the polar 
districts and in the high mountain-chains. He pointed out the 
geological phenomena characteristic of the Carboniferous epoch 
the wide distribution of submarine volcanic products and 
pelagic limestones, the basin-shaped occurrence of the sedi- 
mentary rocks, the absence of large terrestrial and fresh-water 
vertebrates, the absence of purely fresh-water deposits, and the 
insular character of the flora. From all these characteristics, 
Lyell concluded that the northern hemisphere had been 
covered during the Carboniferous epoch by an island studded 
ocean. He then depicted the later epochs, showing that 
during the Secondary epochs large continents arose in the 
temperate regions and produced a change of climate; during 
the Tertiary time the continents in the northern hemisphere 
became more extensive in the direction of the North Pole, while 
the Alps, Apennines, and Pyrenees rose as massive mountain- 
chains, and promoted the gradual approach of the present 
climatic conditions. 

Lyell, in the earlier editions of the Principles, attributed 
little importance to the influence of astronomical causes upon 
terrestrial variations of climate; afterwards he thought these 
more worthy of consideration. More especially the changes in 
the eccentricity of the earth's orbit and in the precession of the 
equinoxes were treated as important climatic factors, and 
turned to account in the explanation of the Ice Age. 

Having opposed the " Catastrophal Theory " in the first 
volume of the Principles, Lyell tried to establish the unifor- 
mity of all natural agencies in past epochs and in the present, 
and both in the organic and inorganic world. 

The subject-matter of the second volume covers the same 
ground as Von Hoffs work, but while the German geologist 


limits himself to a compilation from data recorded in litera- 
ture, Lyell adds his own observations in confirmation of, or 
opposition to, received opinions. The geological action of 
water is first discussed. The destructive and transporting 
agency of running water is demonstrated by numerous examples, 
amongst others particular interest attaches to the admirable 
exposition of the channeling of the Simeto bed at Etna, and 
the erosion of the Niagara ravine. Lyell, in the earlier editions 
of this volume, was of opinion that in addition to stream 
erosion the formation of valleys had been in many cases assisted 
by the occurrence of earthquakes or landslips, or controlled by 
local inequalities in the rate of withdrawal of the ocean, but in 
the later editions he attributed the large majority of valley 
cuttings to river erosion alone. 

Again, in the earlier editions of this volume, ice and glaciers 
received little attention, but in later editions a special chapter 
was devoted to them, and Lyell endeavoured to explain the 
occurrence of erratic blocks as a result of the transportation of 
rock-material by icebergs and floes. 

The chapter on volcanoes and earthquakes includes not only 
a summary of their distribution and manifestations, but also 
detailed descriptions of the district of Naples and Etna. In 
describing Monte Somma, and the volcanoes of the Canary 
Isles and Santorin, Lyell opposes the theory of " Elevation- 
craters," and explains the circular walls of inclined strata round 
a central crater as the ruins of former cones of ejected material. 
In connection with earthquakes, attention is especially directed 
to the accompanying phenomena of crust-fissures and alterna- 
tions of level. The variations at the temple of Serapis, 
near Pozzuoli, are instanced in illustration of the frequency 
with which changes of level may take place in opposite 

The slower variations of level, independent of volcanism, 
and affecting large areas, were not fully treated by Lyell in the 
early editions of the Ptinciples ; but after his travels in 
Scandinavia, a chapter on this subject was introduced, and in 
it Lyell supported the view that the northern portion of 
Scandinavia was slowly rising. 

Lyell attributed volcanoes and earthquakes to the high 
pressure exerted upon the crust by subterranean vapours and 
gases which become heated and endeavour to expand. 
Chemical, electrical, and magnetic influences cause, according 


to Lyell, local rise of temperature in the earth's crust, so that 
larger and smaller reservoirs of melted rock-material may 
accumulate. If the water and gases impregnating the rocks 
are converted into vapour, volcanic eruptions and earthquakes 
ensue. The slow elevations of the ground are also referred by 
Lyell, in the later editions of the Principles ; to subterranean 
rise of temperature and to the consequent expansion of the 
solid rocks, whereas decrease of temperature or the removal of 
gaseous material gives origin to subterranean cavities, inthrows, 
and subsidences. 

Lyell was during the greater part of his life an opponent 
of Lamarckism. In the early editions of the Principles, he 
recognised the occurrence of constant change in the organic 
world, but refused to associate the modification of living forms 
with any definite history of evolution during the successive 
geological ages. He began with the fundamental question 
whether changes in the animal and plant world were still in 
progress, or if organic creation had already arrived at its 
highest development. After discussing Lamarck's views on 
the produption and modification of organs, Lyell enumer- 
ated a number of data regarding the limits of variability 
of wild and domestic species and the results of cross- 
breeding, and expressed his conviction that each species 
had been created with the characteristics still presented by 
it. He allowed that species can to a certain extent accom- 
modate themselves to their environment, but asserted that 
the possible changes were slight, and rapidly accomplished, 
having no influence upon the essential characteristics of 
the species. He held that unlimited variability was further 
prevented by the natural aversion of species in the wild 
state to cross breeding, and by the small fertility of hybrids. 
Lyell afterwards revoked these opinions, a change in his 
views having been effected by the writings of A. R. Wallace 
and Charles Darwin. 

The two famous papers of these authors on the variability of 
species appeared simultaneously in the year 1858 in the 
publications of the Linnaean Society. Darwin's epoch-making 
work on the Origin of Species by Natural Selection was 
published in the following year, and another work of that year 
was W. Hooker's Flora of Australia. 

Lyell, together with the great zoologist Huxley and the 
philosopher Herbert Spencer, at once enthusiastically accepted 


and upheld the newly-founded doctrine of descent. And the 
tenth edition of the Principles, published in 1866, contains an 
excellent account of the leading principles of Darwin's work 
and its bearing upon scientific thought. The chapter on the 
geographical distribution of plants and animals, upon which 
Lyell had spent considerable care in earlier editions, had to be 
completely re-written in the light of Darwin's theory. As it 
now stands, this chapter presents a wealth of fine observations 
and geological conclusions, and is an admirable model of the 
scientific treatment' of a subject. The extinction of species is 
explained through changes both in the organic and inorganic 
world, the appearance of new species is attributed to the 
modification of progenitors. 

In the eleventh edition, Lyell summarised in a special 
chapter the chief features of his work, On the Age of the Human 
Race, which had been published in 1863. In Lyell's opinion, 
all human races and sub-races had sprung from a uniform 
prototype which had originated in one area of the globe. 
All the early human remains gave evidence that the state of 
culture of the first ancestors of mankind had been extremely 
low ; and he saw no reason for assuming that man had taken 
origin through any other agency than the working of those 
universal laws which had determined the origin of species in 
the plant and animal kingdoms generally. 

In the fourth volume of the Principles, afterwards adapted 
as the Elements of Geology, Lyell followed the precedent of 
Deshayes and Bronn in his sub-division of the Tertiary 
deposits. He calculated the percentage of living molluscan 
species present in the successive groups of the Tertiary strata, 
and upon the percentages fixed a definite basis of sub-division 
into Eocene, Miocene, and Pliocene formations. Lyell drew 
his account of pre-Tertiary formations for the most part from 
the text-books of Conybeare and De la Beche. He applied 
the term of primary formations to the plutonic rocks and the 
crystalline schists. Lyell opposed the idea that any funda- 
mental distinction existed between plutonic and volcanic rocks, 
and assumed that granitic and other coarse-grained crystal- 
line rocks might still be in course of formation at great depths 
below the surface, and under the enormous pressure of super- 
incumbent rocks. He showed that granite had been intruded 
at various geological epochs, and was by no means invariably 
the oldest rock, as the Wernerian school had taught. Lyell 


proposed the term metamorphic rock for the crystalline schists, 
which he regarded as normal deposits of sand, clay, or lime- 
stone, subsequently altered in structure by contact with hot 
eruptive material and by subterranean heat. Thus Lyell in 
the question of rock-metamorphism at first preserved precisely 
the attitude of Hutton, but in later years he ascribed the 
processes of crystallisation partially to mechanical causes, more 
especially to strong pressure. 

The appearance of Lyell's Principles was epoch-making. 
Since Werner, no geologist had in such a high degree influ- 
enced and re-modelled the views of geological science. Al- 
though, unlike Werner, Lyell did not impart his ideas directly 
as a teacher, he was personally on terms of intimate acquaint- 
ance with all the greatest of his contemporaries, and no man 
could better appreciate the value of the latent currents in 
scientific thought, nor more skilfully render them intelligible 
to others. 

Lyell was a master of clear exposition; his writings appealed 
to a wide public, attracting many to give more serious attention 
to the study of geology, and establishing it as one of the most 
popular branches of science. 

Throughout his life he was untiring in his denunciation of 
any remnants of the unfounded hypotheses promulgated in 
earlier centuries, and he waged a constant combat against the 
unscientific fabric of the Catastrophal Theory. He taught 
the Uniformitarian doctrine of Hutton and Playfair. The 
earth, in Lyell's opinion, is the scene of never-ceasing change ; 
but while on the one hand he refused to accept the idea of 
universal catastrophes, on the other he saw no direct evidence 
of progress and development in the history of the earth. 
The Uniformitarian doctrine recognises neither beginning nor 
end in the earth's history, and opposes just as strongly as the 
Catastrophal Theory the conception of a progressive evolu- 

Lyell's views were welcomed with enthusiasm in Great 
Britain, and have there had a lasting influence upon the 
methods and tendencies of geological research. In Germany 
also, where Von Hoff had paved the way, Lyell's works 
attained immediate celebrity, and were made widely known 
by several translations. But the personal influence of Von 
Humboldt and Leopold von Buch was still too powerful to 
allow a rapid acceptance of the Uniformitarian doctrine. 


France was even more reserved towards this aspect of Lyell's 
work. The ideas of Cuvier were deeply rooted, and were ably 
supported by Elie de Beaumont and Alcide d'Orbigny. It 
was not until after the death of these two gifted scientists that 
the Uniformitarians could become successful. Many of Lyell's 
opinions, more especially his theories regarding crystalline 
schists, were warmly contested, and his explanation of vol- 
canic phenomena and mountain-making was afterwards found 
insufficient. At the same time, the leading principle of his 
geological teaching that the key to the solution of the events 
of the past is to be found in the study of the natural 
forces still acting has remained as the secure basis of 
all modern geological investigation. The recognition of 
this grand principle gave a new significance to dynamical 
geology, and brought it at once into prominence among 

Sir Henry de la Beche wrote in 1835 an excellent in- 
troduction to dynamical geology, entitled Hoiv to Observe; 
in later editions, the title was changed to The Geological 
Observer. De la Beche followed essentially the same 
method as Lyell, and his book, which is full of new obser- 
vations and facts, may almost be regarded as a supplement 
to Lyell's Principles. 

A. Geological Action of the Atmosphere. The destructive and 
constructive activity of the atmosphere plays in general but a 
small part in the conformation of the earth's surface, and was 
for a long time neglected by geologists. Chemical effects can 
only be produced by the atmosphere in its combination with 
water or living organisms. Mechanical forms of destruction 
are effected by the atmosphere in all regions subject to marked 
extremes of seasonal or diurnal temperature, the wasting of 
the rocks being considerably aided by the strain of alternating 
expansions and contractions. The geographer Livingstone 
was the first who observed that in the African deserts sharp 
fragments sprang away with a ringing tone from the basalt rock 
whenever a hot day was succeeded by a night with very low 
temperature. Other travellers have since confirmed this 
observation, and have ascertained that the so-called " Ham- 
mada " region undoubtedly owes its surface-mantle of angular 
fragments of stone to the destructive effects of rapid variations 
of temperature. 


According to Tietze (1886), the debris in the sterile rainless 
mountain-territories of Persia is chiefly produced by the dis- 
integrating influence of insolation. Again, in the region above 
the snow-line in mountain-chains, the accumulations of debris 
are attributable to the daily alternation of frost and warmth; 
but in most areas the strain is occasioned not so much by the 
rapid change of temperature as by the presence of water in 
the fine rock-fissures, and the pressure exerted during alternate 
freezing and evaporation of the water. 

The geological effects of the wind are of importance. 
Neglecting here the disturbances caused by hurricanes, many 
striking phenomena have been traced to the influence of 
wind-borne sand or dust. As early as 1847, Naumann 
described polished and furrowed rocks near Hohburg, in 
Saxony, and erroneously ascribed the appearance to the 
action of ice. Heim in two papers, in 1870 and 1874, 
showed that the markings on the rocks had been pro- 
duced by wind-swept grains of dust and sand. Similar 
wind scratches had been mentioned by Blake in 1855, and 
by Gilbert in 1874, from the western states of America. 
Zittel, Rolland, Walther, and others have reported how fre- 
quently one may observe wind-worn rocks in the Sahara 
with a polished glassy surface, dotted with cavities, or deeply 
scored and fluted. 

Other phenomena of a more imposing nature in the great 
desert wastes and steppes owe their origin to the wind. In 
the Monument Park of Colorado, the numerous picturesque- 
looking rocky pillars with a narrow basis have been explained 
by Gilbert as remnants left by wind-weathering. The clouds 
of dust borne along by the wind attack chiefly the lower levels 
of the pillars, and reduce these so that the top-heavy upper 
portions are gradually undermined. Similar appearances in 
the Arabian desert have been described by Fraas, who called 
them " Fur-cap Rocks," on account of their characteristic form; 
Walther called them "Mushroom" rocks. More recently, 
" three-cornered" rocks in the dunes and steppes of Northern 
Europe, in the Rhone Valley, in the neighbourhood of Vienna, 
and other European localities, have been attributed to the work 
of the wind. In the Sahara, pillars or table-like eminences 
have been undercut by wind-borne dust and sand, and remain 
as "island rocks" the so-called "gurs of the desert." Long- 
continued action of the wind may hollow out basin-shaped 


cavities, channels, and tunnels in sand-dunes, clay, and loess 
deposits, and in glacier ice. 

The formation of sand-dunes is due to the driving action of 
prevailing winds blowing over flat sea-boards and arid inland 
districts. Lyell, De la Beche, and Elie de Beaumont were 
among the earlier investigators of sand-dunes, and later authors 
have added much to our information on the changes of shape, 
the mode of travel, and the particular kinds of sand character- 
istic of the dunes in various localities. 

The clay deposits so widely distributed in the Pampas of 
South America were considered by A. Bravard in 1837 to be 
aeolian or wind-blown deposits ; but Burmeister regarded 
them as fluviatile in origin, and Santiago Roth as partially 
marine and partially fluviatile in origin, afterwards altered by 
the growth of vegetation. 

The term " loess " has been applied to yellowish clay or 
loam deposits, which were first described in the Rhine Valley, 
and have been found to be present sometimes in remarkable 
thickness over wide tracts of country. Baron von Richthofen 
found in China that these deposits attained thicknesses of 
1500 to 2000 feet, and occurred locally as high as 7000 feet 
above sea-level. He noted the want of stratification and the 
uniform character of loess deposits over great distances, its 
constituents being invariably the finest particles of sand, clay, 
and limestone, no matter what the nature of the ground might 
be upon which the loess had gathered. He further observed 
its porous structure, and showed that the rootlets of grass 
growing on its surface gave origin to pipes similar to those 
which perforated the whole mass. Another important feature 
was the rich occurrence of remains of land molluscs, and of 
herbivorous and other mammals, whereas fresh-water shells 
were absent. Upon the evidence of those observations, Von 
Richthofen concluded that the loess had originated as wind- 
drift. And he pointed out how the dry, fine-grained material, 
readily transported by wind, would naturally tend to accumu- 
late on vast steppes covered with grassy vegetation. At the 
same time, Von Richthofen recognised a "lake-loess" in 
certain localities, in the formation of which water had 

This explanation 01 Von Richthofen's was then applied to 
European occurrences of loess deposits, but the question 
seems to be one which has to be determined independently 


in each locality. A number of geologists have upheld the 
opinion of Lyell and Agassiz that loess was of lacustrine or 
fluvio-glacial origin. Giimbel, in discussing the Bavarian 
loess deposits, drew attention more especially to the effects of 
intermittent inundations of land during the frequent oscilla- 
tions in the retreat of the Alpine glaciers. Laspeyres, 
Baltzer, De Lapparent, and others think that torrential rains 
and other subaerial forms of water have assisted in the for- 
mation of loess. 

B. Geological Action of Water Springs. Water takes 
undoubtedly the first and most important place amongst the 
epigene geological agents. Its chemical and mechanical 
activities are partly destructive, partly reproductive. They 
affect the whole surface, and have not only determined 
the present conformation of our planet, but have also given 
origin to a very considerable part of the rock-material of 
the Earth's crust. 

The authors who have contributed most to our knowledge 
regarding water circulating in the ground are Bischof, Para- 
melle, Lersch, and Daubree. Gustav Bischof wrote the first 
scientific account of springs, illustrating it with his own 
numerous observations on the relations of the underground 
water in the Rhine Valley, on the ascent of springs, on 
Artesian wells, and subterranean water-courses. Many of the 
examples cited by Bischof are now familiar in text-books of 
geology and physical geography. L'Art de decouvrir les Sources, 
a work written by Abbe Paramelle, and translated into 
German by Cotta in 1856, contains excellent hints on 
the methods of finding springs and underground water. 
Paramelle was the most successful water-diviner that ever 
lived ; France owes to him the disclosure of numerous 
springs. In 1864 and 1865 B. M. Lersch published at 
Berlin his books on the Chemistry and the Physics of Natural 
Waters. His Hydro- Chemistry gives especial attention to the 
therapeutic aspects; while in the Hydrophysics there is, in 
addition to his own observations, a carefully collected and 
accurate account of all springs previously mentioned in 
literature. Although the arrangement of this work leaves 
much to be desired, the fund of information which it contains 
gives it permanent value as a book of reference. 

The most complete works on natural waters are those 


published in 1887 by Daubree, 1 under the titles of Les eaux 
sous-terraines a Vepoque actuelle, and Les eaux sous-terraines 
aux epoques anciennes. They treat in a comprehensive and 
scientific manner the origin, the geological occurrence, the 
physical and chemical properties of normal springs, under- 
ground waters, mineral and thermal springs. In an earlier 
work, Daubre'e had described the results of his experimental 
researches on the permeability of different kinds of rock. 
The famous author was not content with a record of his 
own wide knowledge and experience of springs, but exhausted 
all geological and geographical literature on the subject, and 
even referred to special technical estimates and journals. 
In the first volume, Daubre'e devoted a chapter to Artesian 
wells, which he classified according to the geological age 
of the particular water-bearing strata. He distinguished 
common or normal springs and thermal springs whose water 
moves according to hydrostatic laws, from the underground 
waters forced onward by carbonic acid and other gases, or by 
vapour. The second volume contains an account of the 
chemical composition and the temperature of springs and 
underground water, and this is followed by a discussion of the 
Earth's heat and the possible significance of the circulation 
and ingress of water in deep horizons of the crust as a means 
of inducing volcanism. The last volume treats of the geological 

1 Gabriel August Daubree, born at Metz, studied at the Polytechnic 
School in Paris ; began his career as a mining engineer in 1834, and was 
sent to England, Sweden, and Norway on a commission from the Govern- 
ment. As mining engineer and Professor of Mineralogy and Geology in 
Strasburg, he devoted his time to the geological relations of Alsace, and 
published in 1849 a geological map of Lower Alsace, following it in 1852 
by an excellent geological description of this neighbourhood. During the 
years 1857-61 Daubree was engaged in leading and collecting the springs 
of Plombieres, and had opportunities of making important observations 
on the chemical action of thermal water. These were the basis of his 
subsequent experimental attempts to determine the geological action of 
superheated aqueous vapours. In 1 86 1 he became Professor of Geology 
at the Museum in Paris, and displayed untiring energy in this capacity, at 
the same time carrying out a brilliant series of experimental researches for 
which his name will ever remain famous in the annals of geology. From 
the year 1862 Daubree also taught mineralogy at the School of Mines, 
and in 1872 he was made Director of that institute. During the last twenty 
years of his life, lie was a member of the Commission for the publica- 
tion of the special geological map. Daubree died in Paris on the 29th 
May 1896. He was throughout his long and active career greatly revered 
and loved for his amiable disposition and noble, conscientious character. 


work accomplished now and in former epochs by the physical 
and chemical agencies of subterranean water. 

Chemical Action of Water. The importance of water as a 
chemical agent was early recognised, and its corrosive effects 
on rocks were frequently discussed in the older literature. 
K. G. Bischof 1 created a new scientific basis for this field of 
geology. With admirable mastery of the subject, Bischof set 
forth in his Text-book of Chemical and Physical Geology 
(1846-47) all the chemical processes which take place when 
meteoric water and different kinds of aqueous solutions come 
in contact with rocks. He also enumerated and described the 
minerals and rocks according to their chemical composition, 
structure, texture, and characteristic modes of decomposition. 
The new branch of geology thus outlined by Bischof attracted 
great interest, and soon a large number of special memoirs 
made their appearance. One of the best known works on 
mineral decomposition was published in 1886 by Sterry 
Hunt ; it treats for the most part the appearances of decay in 
crystalline rocks. 

Evidences of meteoric weathering of the rocks are shown in 
the changes of colour produced by oxidation, and in the 
removal of the more soluble mineral constituents of rocks. 
The superficial inequalities and degradation produced by sub- 
aerial agents are enhanced by the percolation of water through 
the body of the rock. Continued disintegration of the rocks 
gives origin to soils and coarser debris, and the effect of dis- 
integration may often extend to a considerable depth below 
the surface, gradually' rotting and loosening a whole mass of 
rock. The weathering caused by chemical changes alone 
cannot, however, be regarded as a leading factor in producing 
land-forms. Only the minor features of surface conformation 
are due to the decay of rock in situ. The chemical and 
mechanical forces of water must combine to produce the 
major effects in surface conformation. The rapid removal of 
decaying mineral matter by streams and rivers exposes fresh 
rock surfaces to the disintegrating chemical action of the 

* Karl Gustav Bischof, born 1792 in Niirnberg, studied in Erlangen, and 
was afterwards a university tutor there. In 1819 he. was made extra- 
Ordinary Professor of Chemistry in Bonn; in 1822 he received. the full 
professorship, and contributed in a high degree to the fame of that 
university; died 3Oth November 1870 at Bonn. 


atmosphere. The fresh surfaces in turn decompose, and the 
cycle of chemical transformation and denudation goes on until 
a land area acquires the particular aspect of erosion which the 
eye has learned to associate with certain characters of rock, 
and conditions of altitude, of meteorology, and of drainage. 
The final phases of the work of denudation would be to reduce 
a land surface to sea-level unless other circumstances con- 
spired to prevent complete degradation of the land. 

Highly characteristic forms of weathering may be produced 
in cases where certain portions of a sheet of rock are more 
soluble than others, and become a more easy prey to the pro- 
cesses of disintegration. Heirn has described the scenic effects 
due to the weathering of the different kinds of rock-material 
exposed in many of the mountain plateaux of the Alps. 
Irregular, boldly-hewn outlines and sharp aiguilles are char- 
acteristic forms in the crystalline masses composed of coarse- 
grained granitoid rocks at the higher altitudes of the Alps; the 
finely-serrated ridges with steep slopes and grassy hollows are 
characteristic of the softer shales and clays, while the lime- 
stone and dolomite mountains present alternating terraces and 
prominent escarpments capped by picturesque summit forms; 
in some cases, wide summit-plateaux have been rendered almost 
j impassable by the innumerable petty pinnacles and ravines 
I into which the rock has been weathered. Such summit- 
| plateaux are known as " Karrenfelder." 

The precise origin of the "Karrenfelder" has long been 
a matter of discussion. Among the earlier Alpine authors, 
Scheuchzer and De Saussure attributed these limestone wastes 
to the erosive action of occasional floods. Hirzel, who in 
1829 introduced the term of " Karren," attributed them to 
combined mechanical and chemical weathering acting upon 
perpendicular limestone strata at a certain height above sea- 
level. Among recent authors, Von Richthofen, Heim, Mojsi- 
sovics, and many others explained the jagged and channeled 
character of these high plateaux as in the main a chemical 
effect, due to the action of rain-water containing carbonic 
acid gas in solution, upon the lime carbonate of the rock. 
Favre, on the other hand, associated the particular effect with 
the mechanical operations of glacial water. 

Mojsisovics has described characteristic " Karrenfelder " in 
Carniola like those in other limestone groups of the Alps, "and 
has also observed funnel-shaped depressions on the surface of 


the limestone rocks of that locality, which he attributes to the 
chemical effects of rain-water acting upon the surface. 

These Carniola cavities must not be confused with the 
"dolinas" or "swallow-holes," which are of common occur- 
rence in many limestone areas. The latter are explained as 
insinkings of the surface which have taken place after the sub- 
jacent mass of limestone has been undermined by subterranean 
caverns. Recent geological writings have shown that dolinas 
pre-eminently occur along natural joints and fault-planes, into 
which surface-water readily passes. 

While dolinas, Carniola cavities, and " Karrenfelder" are 
forms of erosion limited to limestone mountains or table-lands 
whose rock is firm and compact, the so-called geological 
" organs " or earth-pipes (sand-pipes, sink-holes) occur chiefly 
in plains whose rock-material consists of soft, fissured lime- 
stone, calcareous conglomerate or gypsum. They are cylin- 
drical or funnel-shaped cavities, generally upright in position, 
and filled partially or wholly by loam, mud, or sand. 

Sand-pipes were first described by Brongniart and Cuvier 
(1811) from the neighbourhood of Paris, and were called 
"Puits Naturels." In 1813, Mathieu described similar pipes, 
narrowing towards the base, at Petersberg, near Maestricht, 
and he called them " Orgues geologiques," the name which 
is still commonly used. Other writers of that time, Gillet- 
Laumont and Bory, explained them as due to the solvent and 
mechanical action of water, infiltrating from the surface, but 
this idea was contested by later writers, and various erroneous 
explanations were offered. Lyell and Prestwich examined the 
earth-pipes and sack-shaped depressions in the chalk of the 
south of England; and they proved beyond doubt that these 
hollows had been eroded by the chemical action of surface 
water rich in carbonic acid, which had primarily found its 
way along any surface crack, or the fine tubular perforations 
formed by the root-growths of the surface vegetation. The 
infilling of sand and clay was derived from the surface layers 
and soil. 

In the Bavarian plain, Penck's recent researches on the 
glacial and interglacial deposits have brought to light many 
fine examples of sand-pipes occurring in the nagelflue or 
rough limestone conglomerate deposits laid down by glacial 
floods. Penck thought the sand-pipes had been hollowed out 
during the period when the nagelflue presented a surface 


exposed to subaerial weathering, and that some of the fine, 
loose clays had afterwards sunk into the erosive and pitted 
surface of the nagelflue rock. In many cases, however, the 
sand or clay in the pipes undoubtedly represents the insoluble 
residue left after the removal in solution of the calcareous 
material in the conglomerate. 

Subterranean caverns always formed a subject of general 
interest in literature, and have given rise to many traditions 
and superstitions. The ancients held them to be entrances 
into the lower world, and the home of nymphs and fauns. In 
later centuries literature peopled them with all kinds of ima- 
ginery beings, fairies, dragons, dwarfs, and evil spirits, and 
ascribed their origin to earthquakes, inthrows of the Earth's 
crust, subterranean fires and floods. 

Towards the close of the seventeenth century, Leibnitz gave 
an accurate description of the Baumann cave in the Harz 
district, and Valvasor examined the caves in Carniola. During 
the following century, although the number of accurate descrip- 
tions increased, little advance was made in the explanation of 
their mode and origin. Kant's Text-book of Physical Geography 
(1801) attributes the origin of caves partly to the erosion of 
the rock by water, partly to outbreaks of fire. 

A new epoch in the literature of caves began with Esper's 
investigation (1770-90) of fossil remains of mammalian bones 
discovered in the French caves. Interest then centred in the 
palaeontological significance of the remains in cave-deposits. 
Cuvier's Recherches sur les ossements fossiles contains an able 
summary of all existing knowledge on the subject of cave- 
remains during the first two decades of the nineteenth century. 
The two brothers Wagner, in Germany, and Buckland by 
his standard work on the Diluvial Remains of England, 
worthily followed Esper's example in collecting information 
and examining ossiferous caverns. The work of Schmirling, in 
Belgium, won well-merited fame on account of its splendid 
illustrations ; it was descriptive of the caverns in the province 
of Liege (1833-34). Marcel de Serres in 1838 published his 
interesting Essay on the Causes which have contributed to the 
Accumulation of Fossil Bones in Caves. 

There is now scarcely any difference of opinion regarding 
the origin of caves. A few caves occur in crystalline or clastic 
rocks ; they are the result either of tectonic disturbances, or 
they represent spaces that have formed during the cooling of 


volcanic magmas. The great majority of caves occur in lime- 
stone, dolomite, or gypsum deposits, and owe their origin 
primarily to the solvent agency of the water circulating through 
the ground. Water as it passes down rock-fissures attacks the 
sides of the rock and widens its own channel, the solvent 
action of the water being greater when it is surcharged with 
carbonic acid. Larger water-courses find their way into the 
widened fissures and may erode complicated systems of tunnels 
and grottoes like those in Carniola, where the subterranean 
streams act both chemically and mechanically on the neigh- 
bouring rock. The streams partially dissolve the material, 
partially carry it away in suspension, or leave a finely-ground, 
insoluble deposit on the floor of the cave known as "red 

The caverns may be further enlarged by collapse of the roof 
from time to time. Frequently surface-material, or organic 
remains imbedded in the deposits above, are thus introduced 
into limestone caverns. A stream or river-channel eroded in a 
limestone bed may be intercepted by the occurrence of clefts 
and swallow-holes, and the superficial stream may thus be 
guided into the system of subterranean intricacies which had 
been previously excavated by the chemical action of under- 
ground water. 

Many caverns were undoubtedly used by the mammals of 
the diluvial period as shelter-places, just as they were after- 
wards used by primaeval man. Often, however, the remains of 
mammals that are found imbedded in the soft clay, sand, or 
loam have been subsequently swept into the caves from the 
surface in consequence of roof collapse. During the latter half 
of the nineteenth century it has been a matter of controversy 
among the authorities on cave remains whether man was or 
was not a contemporary of the cave-bear, the mammoth, the 
woolly-haired rhinoceros, and other extinct mammals in Europe. 
The newest contributions to the literature of ossiferous caves 
deal more with their topography, physiography, and acces- 
sibility. The year 1894 was marked by the publication of two 
pioneer works in this particular aspect of the study of caves, 
the one by the Austrian writer, Franz Kraus, the other by the 
French writer, E. A. Martel. 

The purely mechanical activity of running water is expressed 
in the removal and transportation of loosened fragments of 
rock (ablation), in the grinding action of the transported 


material as it rubs against the floor and sides of stream and 
river-channels (erosion), and in the accumulation of the trans- 
ported material as sediments (deposition). The strength of 
the processes of transportation and erosion depends on the 
volume and velocity, or the impulse, of the running water. 
The transportation power of streams and rivers is under 
ordinary circumstances confined within their channels, but 
although of limited extent it is a phenomenon apparent to 
every observer because of the energy of motion displayed. 
The washing away of rock-material by rain is much less 
apparent, but it is extended over far vaster tracts of country. 

A great incentive was given to the scientific study of surface- 
forms and their causes by the brilliant work of the American 
investigators, Hayden, Powell, Gilbert, Button, and others. 
While they described the wonderful river erosion that had 
taken place in the table-lands of the western states, European 
travellers were making known the characteristic forms of 
erosion in the high and barren territories of inland Africa and 
Asia. There the irregularities of the surface are chiefly due to 
the periodic occurrence of torrential rains and the consequent 
sudden increase or rapid rise of mountain-streams, which rush 
as destructive floods over the table-lands, and retreat and 
diminish no less rapidly than they arose. 

Earth-pillars or pyramids occur in majestic forms in some 
places, and offer more familiar examples of the surface-waste 
accomplished chiefly by rain. In miniature, the formation of 
an earth-pillar may be observed in any thick foliage wood after 
a heavy shower of rain. The drops as they fall from the 
leaves upon the soil sometimes alight upon small pebbles, 
sometimes upon soft humus. The latter is readily washed 
away, the pebbles remain and serve as protecting caps to the 
soil immediately below, so that each pebble and the under- 
lying soil gradually stands out as an individual column. Rain- 
eroded pillars occurring on a grand scale in the Hautes Alpes 
were described in 1841 by Surell; Sir Charles Lyell described 
pillars in the morainic conglomerate in the Tyrol, where the 
larger boulders had served as capping-stones. Hayden made 
known magnificent examples in the conglomerate rock of 
Colorado. Sir Archibald Geikie described their occurrence at 
Fochabers, in the north-east of Scotland, in Old Red con- 

Although many writers of the eighteenth century had devoted 


attention to the erosion effected by running water, their re- 
searches lacked a scientific basis. Guettard had already laid 
hold of the main principles of ablation and erosion when he, in 
1774, set forth the "degradation" of mountains and the whole 
earth surface. Targioni also explained surface conformation 
upon true principles ; while Eber was such an ardent believer 
in Guettard's views that he drew accurate panoramas of the 
Swiss Alps in order that posterity might be enabled to recognise 
subsequent changes in surface conformation. On the other 
hand, De Maillet and Buffon attributed the excavation of 
valleys to the action of submarine currents during the retreat 
of the ocean and the emergence of islands and continents. 
These views were afterwards upheld by Cuvier, De Saussure, 
and Werner, and recur in some measure in the early editions 
of LyelPs Principles. 

Pallas thought the destruction of mountains and the forma- 
tion of valleys was associated with intermittent local floods, 
and this explanation found favour with Buckland, Sedgwick 
(1825), Daubeny (1831), Elie de Beaumont (1829), and many 
others. This theory gave support to the "diluvialists," who 
taught that the Mosaic flood was the final and grandest event 
in a series of inundations, and that which had mainly shaped 
the present surface conformation of the globe. It is interesting 
to remember that Buckland introduced the term denudation 
to express the scouring and hollowing of the continents which 
he attributed to the action of a universal flood. 

But the more natural principles inculcated by Guettard and 
Targioni steadily made their way as the number of geological 
observations increased. Hutton and Playfair, by their admir- 
able treatment of the subject, opened up this field of research 
upon scientific lines. In France and England, during the 
early decades of the nineteenth century, Montlosier and 
Poulett-Scrope explained the origin of many valleys solely as 
a result of the erosive activity of streams, and this was the 
view supported by Von Hoff and Kiihn in Germany. In 1829 
Murchison and Lyell together wrote an essay " On the Excava- 
tion of Valleys," in which they showed their appreciation of 
the potency of river erosion. This explanation then came to 
be currently accepted ; at the same time it is freely admitted 
that many valleys owe their primary origin to tectonic causes. 

Lyell was the first to investigate the work done by erosion 
within a definite period of time. Upon the basis of the 



advance of erosion he made a calculation of the age of the 
Niagara Falls ; his result was afterwards modified by Wood- 
ward and Gilbert. In the second half of this century, the 
rate of river erosion has been examined in minute detail. 
Physicists, geographers, and engineers have combined their 
efforts to obtain an accurate determination of the rate of 
movement in the different parts of a river-course, and the 
corresponding capacity of the stream to transport solid 
material. Geologists especially investigated the abrasive work 
effected by the transported pebbles and sand in deepening 
and widening a river-channel. In American literature, the 
writings that had the most marked influence upon con- 
temporary science were Dana's publications in the Reports of 
Wilke? Exploring Expedition and his Manual of Geology 
(1863), and Newberry's "Description of the Grand Canon ; ' 
in his Report upon Colorado (1861). 

Oldham elucidated in 1859 the erosion of the valleys in 
the Khasi Hills of India, Rubidge investigated the work of 
water in eroding the South African valleys, and in 1870, 
Blanford gave an account of the Abyssinian valleys. Green- 
wood, Jukes, Whitaker, and Topley dealt exhaustively with 
the erosion of English river-valleys. In 1869, Riitimeyer 
published at Bale his famous work on Valley and Lake 
Formation, which has exerted a permanent influence upon 
geological thought. Riitimeyer endeavoured to prove that the 
majority of the mountain-valleys in Switzerland, including the 
largest river- valleys, had originated only in virtue of stream 
erosion, but that long geological periods had been occupied 
in the excavation of the channels. The commencement of 
the valley erosion had been coeval with the uprise of the Alps, 
but erosion had not always progressed with the same intensity. 
Erosion had worked from the foot of the mountains backward 
and upward to higher levels, consequently the different por- 
tions of a river-course might present distinct types of erosion 
(waterfalls, lakes, rivers, etc.). A sketch-map illustrating the 
history of the lakes and rivers of Switzerland accompanied 
Riitimeyer's work, and was of special value as the first bold 
attempt to classify the Swiss valleys according to their geological 

The American geologist Gilbert, in 1877, in his Geology of 
the Henry Mountains, established the fundamental laws of river 
action in the erosion of valleys. The researches of Powell and 


Button in Colorado, and of Davis in Pennsylvania, corroborated 
Gilbert's results. These American geologists demonstrated con- 
clusively the backward progress of erosion during the excavation 
of a valley, and the definite relation that exists between the 
gradient of a river-bed and the excavating force of the river. 
Hence the base-level of valley erosion could be ascertained with 
great accuracy. 

Following Riitimeyer's method, W. Morris Davis depicted 
the different stages in the development of a valley. In its 
juvenile stage the rushing stream furrows narrow channels 
with deep banks; in its mature stages the angle of declivity 
is less, the valleys become broad and the banks gently sloped ; 
in the older stage the valley-bed is worn away to the base- 
level of denudation. Should any crust-movement locally 
lower the base-level, then the cycle of valley-formation begins 
anew. Davis then tried to determine the geological age of 
various eroded plains and their drainage systems. 

The publications in Europe during the last two decades 
of the nineteenth century are in the main based upon 
the principles enunciated by Riitimeyer and the American 

A difficult problem is presented by the transverse valleys 
that cut across mountains, plateaux, and sometimes across 
several parallel chains. The theory of origin by tectonic faults 
seemed especially applicable in their case, and many of the 
best authorities at the present day support this explanation. 
But Medlicott, in 1865, in the Memoirs of the Indian Geological 
Survey, pointed out that not only was the central chain of the 
Himalayas clearly older than the lateral Pliocene chains, since 
the materials of the central chain had contributed to the rocks 
of the lateral chains, but the Himalayan river-courses had also 
been defined previous to the uplift of the Pliocene chains, and 
had successfully continued to erode their valleys along the old 
lines while these chains were being slowly uplifted. 

J. W. Powell expresses the same idea in more precise terms 
in his explanation of the course of the Green River across the 
Uinta Range, and of the Colorado River in its deep cutting 
through the Arizona plateaux. In both cases the river passes 
from younger strata into older; and Powell's explanation of 
the apparent enigma is that after the river had eroded its 
channel rocks were uplifted at one portion of its course, but 
so slow was the rate of uplift that the river was enabled to 


deepen its channel either proportionately or more rapidly, so 
that it was never diverted from its former course. 

Independently of Medlicott and Powell, Tietze arrived at 
a similar explanation of the origin of transverse valleys in the 
Elburz mountains in Persia, and of the Iron Gates of the Danube 
across the Transylvanian mountains. Tietze refers the begin- 
ning of such transverse valleys to a period when the chains 
across which they pass had no existence as such, but still 
formed part of a continental plain. The Swiss geologists, 
Heim and Briickner, support this theory, but it has been op- 
posed by Lowl, who accepts Riitimeyer's explanation that the 
backward erosion of valleys may finally cut through watersheds 
and even entirely through mountain-chains. 

Within the last few decades geographers have made great 
advances in the detailed knowledge regarding the erosion of 
river-channels, the diversion of river-courses, the serpentine 
windings, the recession of watersheds, and the causes of 
special forms of erosion such as river-terraces and pot-holes. 
These are fully treated in Penck's Morphologic (vol. i., pp. 

2 59-3 8 5)- 

The first exact reports on the quality and kinds of material 
transported by rivers were those made by Mr. Everest (1832), 
who determined that the average annual amount of detritus 
covered by the River Ganges amounts to T ^ by weight. 
Under the auspices of the United States Government, a very 
important series of investigations were carried out on the 
Mississippi river. The accurate results obtained there by the 
engineers Humphreys and Abbot showed that the proportion 
of material held in suspension by the river was y*W by weight, 
and that the total weight of earthy matter annually transported 
to the Gulf of Mexico by the Mississippi river amounted to 
812,500,000,000 pounds. (Report upon the Physics and 
Hydraulics of the Mississippi, 1861.) 

Nearly all the great rivers have now undergone examination 
in this respect, and the results obtained have given geologists 
a much clearer conception of the actual rate of progress of 
subaerial waste. In an able essay, entitled On Modern 
Denudation, published in 1868, Sir Archibald Geikie made 
careful calculations of the amount of material annually 
transported by rivers, and showed how an irregular surface 
can be entirely levelled to a plain by the subaerial agencies of 


A large number of interesting observations have also been 
made by geologists on the wear and 'tear that takes place on 
broken rock-material in the course of its transport by a river. 
Professor Daubree demonstrated experimentally the effects of 
mutual abrasion. By subjecting fragments of granite and 
other rocks to artificial means of trituration and friction, he 
produced the rounded water-worn forms of pebbles and the fine 
sand and mud characteristic of river detritus. He also 
showed that the chemical action of the water appreciably 
contributed to the dissolution of the fragments. The de- 
position of the transported material over alluvial tracts at the 
entry of rivers into fresh-water lakes and the ocean, was fully 
and ably treated in the writings of De la Beche, Lyell, and 
Elie de Beaumont. And since the publication of the earlier 
works, the literature has been enriched by the special 
contributions of Delesse, as well as by the excellent exposition 
of the subject contained in the text-books of Geikie, De 
Lapparent, Von Richthofen, and others. 

The speculative aspect of the invasions of the land by the 
sea had been frequently dealt with in the writings of the 
Greek and Roman philosophers. Careful historical records 
had also been kept of the more striking changes in the 
Mediterranean coast-lines. Von Hoff, in his account of the 
inroads made by the sea, embodied all the previously known 
data, both historical and scientific, regarding the mechanical 
action of breakers, tides, and currents in the erosion of a 
coast-line. New observations were added by De la Beche and 
Charles Lyell ; and Oscar Peschel in his Physical Geography 
(1879) discussed the particular form of coastal outlines in 
their relation to the destructive action of breakers. 

While PeschePs views of the action were based upon a 
supposed stationary condition of the coasts, Baron Richthofen 
brought new life to bear on the subject when he pointed out 
that the denudation of a coast may be going on contem- 
poraneously with a movement of elevation or subsidence of 
the land (China, vol. ii., 1882). In the former case, the 
breakers of the retreating ocean can only erode a denudation 
slope parallel with the original outline of the beach, and the 
depredations of atmospheric weathering tend to rapidly 
produce an irregular appearance of .the surface. As the 
movement ceases, a marine terrace is formed, or if several 
pauses occur at periodical intervals, a series of terraces is 


formed. In the case of a subsiding coast, the effect of 
wave-action would be to destroy resisting cliffs and obstacles 
as the sea advanced inland, and thus to give origin to a 
submarine plain. Sir Andrew Ramsay and Mr. Uavison had 
described in general terms the "abrasive" work of the breakers, 
and shown how as the level of land became degraded by 
subaerial forces of denudation, the margin next the sea 
arrived at its base-level of erosion, and sank as a denuded 
plain below the advancing sea. Such a plain was called by 
Ramsay a plain of submarine denudation. Von Richthofen 
adopted the term "abrasion," and used the expression a "plain 
of abrasion" to signify more particularly a submarine platform 
whose surface had been abraded during subsidence of the 
land by the destructive action of marine breakers and currents. 
Sir Archibald Geikie, on the other hand, thinks that submarine 
platforms have owed their degradation of level essentially to 
subaerial agents of erosion, and that they represent land 
surfaces which had arrived at the base level of erosion before 
they were submerged, the action of the waves merely 
completing the process of levelling. De Lapparent, Penck, 
and many other geologists similarly explain the origin of 
plains of denudation by subaerial erosion. 

Recent maps of Oceanography show at a glance that sub- 
marine platforms sometimes extend for many square miles as 
a marginal belt around continents or islands, and geographers 
find it very difficult to determine the precise conditions to 
which these " peneplains " owe their existence in the various 
regions. Several German and Austrian geographers, following 
Richthofen's methods, have conducted special investigations 
on this subject during recent years (Fischer in 1885 and 
1887, Kriimmel 1889, Philippson 1892, Penck 1894). 

The old idea, favoured by De Maillet, Buffon, Cuvier, and 
others, that marine currents played an important part in the 
configuration of the globe, has been proved fallacious. Marine 
currents lose their strength as they come into the shallow areas 
near the coast; they increase in strength where they pass 
through narrow channels, especially where, as in the Straits of 
Gibraltar and the Bosphorus, they sweep between two seas. 
The origin of the deeper furrows and basins in the floor of the 
ocean can in very few cases be explained by submarine erosion. 
As a rule, they represent either continental valleys that have 
been submerged or troughs formed by crust-movements. 


Under Buckland's term of "denudation," geology at the 
present day signifies that process which, if continued far enough, 
would reduce all surface irregularities of the globe to a uniform 
base-level, but the general term makes no premisses about the 
particular agencies affecting the removal of surface material. 
The chief qualifying terms in common use at the present time 
are " subaerial," " marine," and " submarine." Subaerial denu- 
dation practically comprises all the natural operations by which 
land-areas can be lowered ; it includes the action of wind, of 
running water, and of ice. Marine denudation, so far as it 
affects land-areas, is limited to a narrow marginal belt. Sub- 
marine denudation is used to signify the wearing or scouring 
action of the water, or any chemical processes affecting the 
floor of the ocean. 

Hand in hand with the advance of scientific thought regard- 
ing the causes and effects of recent denudation, there developed 
among geologists a clearer apprehension of the evidences of 
denudation in the past. In the beginning of the nineteenth 
century, Berzelius and Hisinger had suggested that the sedi- 
mentary series (Silurian) present in West Gothland might be 
only remnants of a much wider sheet of deposit which had 
been for the most part washed away. An important step in 
advance was made by Sir Andrew Ramsay in his work On the 
Denudation of South Wales (1846). Ramsay showed that the 
Palaeozoic sedimentary .strata of Cornwall and South Wales 
were composed of fragments derived from older rock-material, 
that therefore this district had suffered immense loss by denuda- 
tion in very early geological epochs. 

Emmrich in 1873 had drawn attention to the evidences of 
transportation of Triassic rocks in Southern Thuringia, and in 
1880 Biicking made an approximate estimate of the amount of 
denudation, calculated from the thickness and extent of the 
derived deposits. The researches of Pomel and Zittel in the 
Libyan Desert and the Algerian Sahara, with their numerous 
isolated hills, proved that this area had been denuded on a 
scale of remarkable magnitude, probably by subaerial agencies 
during the Pliocene and Diluvial periods. Dutton's famous 
work on the Grand Canon showed that the extensive denuda- 
tion of the Colorado lands had been likewise accomplished 
within comparatively recent geological epochs. 

Neumayr, who made in 1885 a special investigation of the 
original distribution and extent of the Jurassic formation, 


found many evidences leading to the conclusion that there 
had been enormous denudation of Jurassic deposits in certain 
areas. These few examples suffice to show how cautiously 
one must use the present disposition of geological forma- 
tions as a basis for the reconstruction of maps portraying 
the distribution of continent and ocean in past geological 
epochs. It is almost impossible in the case of the older sedi- 
mentary deposits to ascertain the amount of denudation they 
have incurred in past ages. 

Mechanical Sediments in ihe Ocean. In the eighteenth 
century, De Maillet had investigated the deposition of sediment 
on the floor of the ocean. Early in, the following century, the 
writings of De la Beche, Lyell, and Elie de Beaumont provided 
able chapters on sedimentation, and explained the deposition 
of detritus over alluvial tracts, and on the floor of fresh-water 
lakes, inland seas, or the ocean. The observations of these 
authors were made chiefly on the English, French, and Medi- 
terranean coasts. 

A classical work on the subject, The Lithology of the 
Sea-Floor, was published in 1871 by the engineer and geologist, 
M. Delesse. Beginning with a full exposition of the origin 
and constitution of the material transported from Continent to 
Ocean, Delesse next describes the sediments throughout the 
whole sea margin of France, and then depicts those in the 
other seas of Europe and along the coasts of North and Central 
America. Three coloured maps show the distribution and the 
petrographical character of the marine sediments in these 
areas, and illustrate for the first time the great variety in the 
nature of the deposit on one and the same coast. Delesse, 
applying his knowledge of the modern formations of sediments, 
was enabled to reproduce in cartographical form the probable 
distribution of land and sea in France during the Silurian, 
Triassic, Liassic, Eocene, and Pliocene periods. Rough 
sketches of a similar kind had been previously prepared by 
Elie de Beaumont, by Lyell and Dana. Those of Delesse 
have been a model for all subsequent efforts in this direction, 
and have never been surpassed. The Atlas by Canu, pub- 
lished in 1895, provides more geological detail, but the maps 
are less clear. 

While the work of Delesse comprises all the important facts 
known up to the year 1871 about the constitution of littoral 


sediments, it does not enter into the consideration of deep-sea 
deposits. The samples brought by Captain Brooke, in 1857, 
from the Kamtschatka Sea, at depths between 900 and 2,700 
fathoms, were examined by Bailey, who demonstrated the 
existence of abyssal pelagic sediments composed of the 
shells and skeletons of Foraminifera, Radiolarians, and Di- 
atoms. Similar deposits at smaller depths had already been 
proved by the researches of Ehrenberg, Joseph Hooker, and 
Pourtales. In 1857, soundings were commenced in the 
Atlantic Ocean, when it was desired to establish cable com- 
munication between the Old and the New Worlds. Samples 
of the deposits of the ocean-floor were given to Huxley by 
Captain Dayman, and the examination of these resulted in an 
accurate description of Globigerina Ooze. Between 1860 and 
1870 many soundings and dredgings were taken in the Atlantic 
Ocean, and the reports of Wyville Thomson, Carpenter, and 
Pourtales added valuable scientific information about the 
pelagic faunas and sediments. 

Oceanography was signally advanced by the results of the 
Challenger Expedition. The English ship Challenger sailed 
for four years (1872-76) on a voyage of exploration of the 
great ocean basins. The material brought, home was investi- 
gated and reported upon by the most eminent scientific 
specialists of the day. The final report by Murray and Renard 
(London, 1891) contains an exhaustive exposition of the 
whole field of modern knowledge regarding pelagic deposits. 
A comparison of this masterly work with that of Delesse, 
shows what a grand accumulation of new facts had been 
obtained during the twenty years that had elapsed, and 
more especially how deep a debt of gratitude science owes 
to the promoters and enthusiastic workers of the Challenger 

In the Challenger Report all deep-sea deposits are classed 
as "terrigenous" or "pelagic" in origin (ante^ p. 183). The 
former are distributed for the most part along the coast-line, 
upon a shallow submarine platform adjacent to the shore, and 
a gentle slope descending to lower depths. The pelagic 
deposits owe their origin partly to the organic world, partly 
to submarine volcanoes, and cover the floor of the open 
ocean. All the different kinds of sediment are described in 
the Challenger Report macroscopically, microscopically, and 
chemically; their exact occurrence is entered upon maps of 


the soundings, and a general map is drawn representing their 
geographical distribution. 

The deposits due to the mechanical action of water are 
almost entirely of terrigenous origin. River detritus and the 
sand and mud produced by wave action are floated seaward 
and spread on the floor by the action of marine currents. 
The blue colouring matter in terrigenous deposits is sometimes 
an organic substance, sometimes iron sulphide ; the green 
colour is due to glauconite, the red colour to yellow iron ore. 
On the coasts where volcanic rocks predominate, marine mud 
consists of finely triturated volcanic material. The pelagic 
" Red Clay " so widely distributed in the Pacific and Indian 
Oceans as a rule occupies the deeper stretches of the ocean- 
floor. According to the investigations of Murray and Renard, 
deep-sea " Red Clay " is essentially composed of strongly de- 
composed volcanic material, originating partly from subaerial, 
partly from submarine eruptions, and also contains "numerous 
remains of whales, sharks, and other fishes, together with 
zeolitic crystals, manganese nodules, and minute magnetic 
spherules, which are believed to have a cosmic origin " (see 
Murray, "Oceanography," Geographical Joiirnal, 1899). The 
Red Clay deposits pass, in most places, quite gradually into 
the calcareous oozes. 

A special interest attaches to the chemical changes that take 
place in the waters of the ocean or the ocean-floor by the 
action of the sea-water upon the various kinds of sediment. 
The zeolitic, manganitic, and phosphatic contents of the Red 
Clay betray what an important part has been played by 
chemical interchange in determining the actual constitution of 
this extensive deposit. The more accurate knowledge of the 
ocean-floor has thrown a flood of new light upon all researches 
regarding the deposits of past geological epochs, their correla- 
tions, their origin, their constitution, their subsequent trans- 
formations, chemical and dynamical. It is not too much to 
say that the Challenger Expedition marks the grandest scientific 
event of the nineteenth century. 

Chemical Deposits in Water. Chemical, technical, medical, 
and geological works have published innumerable analyses 
of the chemical deposits separated in springs, underground 
water, rivers, and lakes. Gustav Bischof summarised the 
most important results of this extensive literature in his 


Chemical Geology^ and the later work of J. Roth (1879) con- 
tains an even fuller account of this subject. The deposits 
formed in a purely chemical way, without any assistance from 
organisms, have been so systematically and ably elucidated by 
Bischof and Roth, that there is now scarcely any difference of 
opinion among geologists regarding the origin of calcareous 
tufa, travertine, ochre, hydrous ferric oxide or " moorband pan," 
siliceous sinter, fresh-water limestone and dolomite, and other 
kinds of spring and fresh-water deposit. Mellard Reade has 
more recently calculated the amount of material held in 
chemical solution in rivers and transported by them to the sea. 
If his figures are confirmed by further analyses, they will 
form the basis of far-reaching conclusions. 

The earliest analyses of sea-water made in the nineteenth 
century were those of Vogel, Marcet, Wollaston, and Bibra. 
In the year 1845, the famous Copenhagen chemist, Forch- 
hammer, began a series" of researches on the composition of 
sea-water, and twenty years later his admirable treatise on 
the subject was published. Bischof and Roth also investi- 
gated the composition of sea-water. 

It may be said in general that no chemical deposits form on 
the floor of the open sea, as the immense volume of sea-water 
holds the substances in solution. Only very small quantities 
of lime carbonate and magnesium carbonate or dolomite seem 
to be deposited under certain conditions. 

In inland salt seas, gypsum and rock-salt separate out in 
large quantities and form thick floor deposits for example, in 
the Great Salt Lake of Utah, the salt seas of Central Asia and 
Southern Russia, in the Shotts of the Sahara, and in many 
bitter lakes. The process of the spontaneous evaporation of 
sea-water was studied by Usiglio (1849) on Mediterranean 
water, and by his laboratory experiments he determined the 
order in which the various salts are deposited during progres- 
sive concentration of the brine liquor. Usiglio's results were 
then applied in the production of salt from sea-water for 
commercial purposes. 

An attractive account of the saline basins in the North 
Caspian Steppes was contributed to Erman's Journal by Baer 
in 1854. The salt deposits were carefully described, and the 
author concluded from the distribution of the basins that the 
Caspian Sea was formerly of far wider extent. Baer demon- 
strated that the waters of the Caspian Sea are still diminishing 


in volume, and the salt deposits steadily accumulating in its 
shallow offshoot called the Karaboghaz. 

Gilbert arrived at a similar conclusion with regard to the 
Great Salt Lake of Utah. The surface of this lake is now at a 
height of 4,250 feet above sea-level, but old lacustrine terraces 
are present at higher levels round its margins, the highest being 
940 feet above the present surface-level. Gilbert explains the 
shrinkage in the size of the lake as a result of local meteoro- 
logical changes. Owing to the diminution in the rainfall and 
in the volume of inflowing rivers, the surface of the lake sank 
below its former outlet, and the lake-water became more and 
more saline until it arrived at its present degree of concentration. 

The most complete accounts of the Dead Sea and its salt 
formations are those given by O. Fraas and L. Lartet. The 
deposition of salt and gypsum takes place every summer, when 
evaporation is rapid, and a layer of mud is deposited during 
the intervening period of diminished evaporation. 

Geologists early recognised the agreement of the chief 
products of super-saturation of existing sea-water and salt lakes 
with the layers of rock-salt in ancient geological formations of 
the crust. Fichtel (anfe, p. 88) had expressed the view that 
the Transylvanian salt-deposits represented evaporation pro- 
ducts formed from sea-water, which had found ingress into 
underground cavities after the consolidation of the crust. The 
upright position of salt-veins at Bex, in the Rhone Valley, led 
the younger Charpentier to the conclusion that the salt must 
have originated from sublimation in crust-fractures. 

Several geologists about the middle of the nineteenth century 
suggested the probability of a plutonic origin of salt-layers after 
the manner of the massive crystalline rocks. This view was 
warmly repudiated by G. Bischof, who rightly argued from his 
knowledge of the recent deposits in the Dead Sea and the 
North Caspian depressions, that the salt-deposits within the 
earth's crust had taken origin in the same way from ancient 
basins of water as they became desiccated. The salt-layers of 
Stassfurt and Kalusz remained for a long time an unsolved 
problem, since no direct comparison could be found between 
them and any natural deposit in present course of formation. 
At Stassfurt, thin beds of highly deliquescent salts succeed the 
main salt-layer; first, a thin band of anhydrite, then a bed of 
deliquescent chlorides, including some sodium chloride, then a 
bed of potassium and magnesium sulphate, and lastly an upper 


layer of double chlorides of potassium and magnesium. These 
salts, in spite of their high deliquescence, have been preserved 
from denudation in an exceptional degree owing to the presence 
of a thick protective surface- man tie of clay. 

The subject was treated by E. Reichhardt (1866), and still 
more successfully by F. Bischof (1875), upon the recognised 
principles of desiccation. 

Ochsenius in 1875 set forth the nature of the conditions 
under which the Stassfurt succession might have been formed 
in nature. He supposes a bay or a sea-basin connected with 
the main ocean only by a narrow channel, which was periodi- 
cally closed by crust-movements, or by the accumulation of 
sandbanks or submarine bars which could be surmounted only 
at the highest tides. During the period of closure, wherever 
the evaporation exceeded the inflow of fresh water, a concen- 
tration of the salt water would take place, and gypsum, an- 
hydrite, and salt would be thrown down. If a permanent 
isolation were finally effected, and desiccation brought about in 
this natural salt-pan, it followed that the salt of the mother- 
liquor must separate out completely in accordance with the 
order of their solubility. 

C. Geological Effects of Ice. The importance of ice as a geo- 
logical agent was much later in being recognised than that of 
water, and this is readily explicable from the more limited 
occurrence of ice and the less striking character of its action. 
Moreover, the regions where ice displays its grandest effects 
were still avoided in the eighteenth century, and were only 
familiar to a few bold explorers. The river and lake ice of the 
continents, and the ocean ice of the Polar districts have little 
interest for geologists, since they cannot help much in eluci- 
dating the work of ice in the past epochs of the earth's history. 
Greater interest attaches to the glaciers of the- mountain- 
systems and the inland ice-sheets of the Polar continental 

Glaciers are mentioned for the first time in literature as 
a subject of scientific investigation in Scheuchzer's Reisebe- 
schreibung der Schweizer A/pen. The indefatigable and 
learned scientist records the few observations of Simler and 
Hottinger on the origin and movement of glaciers, and after 
a careful description of several glaciers visited by himself, 
he explains the movement as a result of the infiltration and 


freezing of water in cracks and other spaces. Scheuchzer is 
thus the founder of the Theory of Dilatation, afterwards advo- 
cated by Charpentier and Agassiz. The pastor Altmann in 
1750, and Gruner in 1760, wrote about glaciers without bring- 
ing forward anything essentially new. They referred the 
movement of Alpine glaciers to the sliding of the ice on a 
sloping base. Neither Scheuchzer nor the two last-named 
authors had given special attention to the moraines. 

A short paper, published in 1787, by Kuhn in Hopfner's 
Magazin Jur Helvetiens Naiurkunde, contained not only 
an excellent description of the Grindelwald glacier and its 
moraines, but the author also followed the old moraines, and 
concluded that the glacier had formerly been of far greater 
extent. De Saussure's famous Book of Travels (1796-1803) 
contained accurate descriptions of the glaciers in Wallis, the 
Bernese Oberland, and the Mont Blanc group. The form, 
arrangement, composition, and movement of the moraines were 
all carefully handled. Saussure also used the moraines as a 
means of determining the extent and the advance and retreat 
of the glaciers, without, however, drawing any general con- 
clusions. Strange to say, he associated neither the smoothness 
of the glacier floor nor the " Roches moutonnees " with the 
movement of ice-masses. 

Saussure had in F. G. Hugi a successor who accomplished 
much for the knowledge of Alpine glaciers. A fearless moun- 
taineer, Hugi explored the upper reaches of the glaciers; in 
1827 he even built a hut on the Finsteraar glacier for his 
convenience in carrying on researches. He observed many 
facts about the structure and constitution of the snow, firm, 
and ice at different heights, about the position of the firm line, 
about fissures and crevasses which had escaped previous 

In the year 1821, at the Eighth Annual Congress of the 
Swiss Society of Scientists, the engineer Venetz read a paper on 
the variations of temperature in the Swiss Alps, which con- 
tained wholly new conceptions. This important paper was not 
published until 1833. Venetz called attention to the fact that 
there were not only moraines connected with the advances and 
retreats of the Alpine glaciers, but that in addition to those, 
morainic walls occurred at a greater distance from the present 
glaciers, and they gave evidence of glaciation on a scale of 
enormous magnitude in some former period. In 1829 Venetz 


gave confirmatory evidence in favour of the much grander 
dimensions of the Alpine glaciers in a past age. In addition 
to the morainic walls he referred to ice transport of the erratic 
boulders dispersed in such numbers in Alpine valleys and 
across the plains at the base of the Alps, and throughout 
Northern Europe. 

Under the influence of Venetz, Charpentier (ante, p. 103), 
director of salt-works and a personal friend of Venetz, became 
deeply interested in glacial studies. Starting with the idea 
that his friend had formed erroneous conceptions, Charpentier 
soon became a convert, and declared himself openly in their 
favour. He gave in 1834 a memorable address at Lucerne, in 
which he showed that the large erratic blocks could not have 
been transported by water; that the frequent scratches and 
deep grooves on the rocks in Wallis are the work of glaciers; 
that the occurrence of morainic walls and erratic blocks remote 
from the present glaciers proved incontestably the former 
presence of longer, wider ice-rivers. He thought the greater 
glaciation of the Alps in a former epoch might be explained 
by the greater height which the Alpine summits had once 

Enthusiasm for the subject was now thoroughly aroused in 
Switzerland. Acting on the initiative of Charpentier, and 
under his personal guidance, Louis Agassiz, in the summer of 
1836, made his first glacial studies at Bex on the erratics in 
the Rhone Valley, and explored the glaciers of Diablerets and 
in the neighbourhood of Chamonix. His fellow-student and 
friend, Karl Schimper, accompanied Agassiz on most of these 
excursions. The genial Munich botanist had already made a 
study of the erratics on the Bavarian plain at the base of the 
Alps, and had explained them as masses transported from the 
mountains by floating icebergs. 

Schimper, from numerous observations on the variation of 
past floras and faunas, formulated his conception of alternating 
epochs of desolation and re-animation. He identified the 
youngest period of desolation as that during which the erratics 
had been distributed, and regarded it as a great Ice Age. 
Schimper embodied these ideas in courses of lectures delivered 
in Munich to a small circle of friends. In the winter of 
1836-37, Agassiz also gave a course of lectures at Neuchatel 
on glaciers and the Ice Age, and copies of an ode written by 
Schimper on the Ice Age were distributed by the poet 


himself to the members of Agassiz' class. In that poem, 
which was re-published in 1841, the epoch of ice was thus 
depicted : 

" Ice of the Past ! of an Age when Frost 
In its stern clasp held the lands of the South, 
Dressed with its mantle of desolate white 
Mountains and forests, fair valleys and lakes ! " 

In July 1837, Agassiz 1 laid a report of his glacier studies 
before the Annual Congress of Swiss Scientists, in which he 
expressed his view that a strong fall of temperature had taken 

1 Louis Jean Rudolph Agassiz, the son of a Swiss Protestant pastor, 
was born 28th May 1807 at Motiers, on the Murten Lake (Canton 
Waadt). He was educated first at the academy of Lausanne, and later 
studied Medicine and the Natural Sciences at Zurich, Heidelberg, and 
Munich. While still a student he occupied himself with the study of 
recent and fossil fishes, and after the publication of the first part of his 
great work on Fossil Fishes he came into personal relations with Cuvier 
and Humboldt in Paris. In 1832 the already world-renowned young 
naturalist was appointed Professor at the Academy of Neuchatel, and 
made it an active centre of scientific investigation. In 1834 he paid a visit 
to England for the purpose of studying the British fossil fishes, and in the 
same year received from the Geological Society the Wollaston medal. In 
the summer of 1836 he began his glacial studies under Charpentier's 
direction, and pursued them for ten years with striking success in the Swiss 
Alps, in Great Britain, and afterwards in North and South America. In 
1846 he crossed the Atlantic and delivered courses of lectures in various 
towns, and was appointed Professor of Zoology and Geology in the 
University of Cambridge, U.S.A., in 1847. He went as Professor of 
Comparative Anatomy to Charleston in 1851, but returned in 1853 to 
Cambridge. In 1859, he founded there, with pecuniary aid from private 
individuals and also from the State, the fine Museum of Comparative 
Zoology. His public lectures, also the instruction he gave at Harvard 
College, his numerous publications, exhibited such an almost unique 
activity as to procure him great popularity. His interest in his magnificent 
Museum, the opportunities to follow his zoological studies, and to take 
part in various marine expeditions which his residence near the sea 
procured him, and, not least, the enthusiastic reception which he had 
received in North America, and the influence he could have there on the 
whole development of scientific life, induced Agassiz to refuse many 
tempting offers to return to his native land, and also the offer of an 
appointment in Paris as a Professor in the Museum. He became a 
naturalised American, and died in Cambridge, Mass., on the I4th December 
1873. Besides his epoch-making work on fossil fishes and his glacial studies, 
Agassiz published valuable monographs on fossil and recent Echinids and 
Molluscs, and numerous zoological works. In 1868 a report on his 
journey to Brazil appeared, and was followed in 1871 by another on a 
deep-sea investigation between Cape Horn and California. To the last 
Agassiz combated Darwin's theory of evolution. 


place previous to the upheaval of the Alps ; enormous masses 
of ice had been formed and had extended over the surface as 
far as erratic blocks and the scratched and polished rocks 
could now be observed. 

Schimper took umbrage that the priority of the Ice Age 
Theory should, in his opinion, have been stolen from him by 
Agassiz, and the friendship of the two Alpinists was broken. 
Schimper afterwards confined himself to the publication of his 
Ode and of a scientific communication, which he made to 
the Annual Congress when it met in Neuenburg. Agassiz, 
however, continued the researches with unabating zeal; in 
company with Desor and Studer, he visited the glaciers of 
the Bernese Oberland, the Mont Blanc group and the Monte 
Rosa group, and published the results of his investigation in 
1840, in a work written in French, and immediately translated 
into German by Carl Vogt. 

This work, which Agassiz suitably dedicated to the founders 
of modern glacial research in Switzerland, Venetz and 
Charpentier, contains the first general exposition of glacial 
phenomena in the Alps. For much of his information Agassiz 
relies upon Saussure and Hugi, but he devotes far closer 
attention to the moraines and introduces the terminology now 
in common use (end moraines, lateral moraines, median 

Agassiz explains the formation of median moraines through 
the junction of two lateral moraines, but, like previous authors, 
he fails to appreciate the existence of ground-moraine, although 
he clearly explains the etching action of sand-grains on the 
rocks at the bottom of the glacier. With respect to the for- 
mation of glaciers from descending firn, Agassiz agrees with 
the conclusions previously arrived at by Scheuchzer, Saussure, 
and Hugi. He regards Scheuchzer's infiltration and dilatation 
theory as the best explanation of glacier movement. 

Agassiz recognises the great merit of Charpentier in having 
drawn attention to the scouring, furrowing, and polishing of 
rocks effected by glaciers, and strongly emphasises the work 
of denudation effected by glaciers on the rocky floor over 
which they move. He describes the hummocky bosses of 
rock exposed to view on the retreat of a glacier, and notes 
their characteristic striated appearance, and the parallelism of 
the striae and grooves on their surface, with the direction that 
had been followed by the glacier. 


Agassiz can see no sufficient evidence of any periodic 
regularity in the advance and retreat of glaciers ; the variations 
of the glaciers represent, in his opinion, the result of two 
opposing forces the forward movement of the ice-masses 
and the solvent action of the atmosphere. The precise dimen- 
sions of a glacier are, he writes, essentially correlated with 
climatic conditions ; a change of climate produces a corre- 
sponding increase or diminution in the size of a glacier. 
Agassiz regards the testimony in Switzerland as absolutely 
convincing, that the Swiss Alps were formerly almost wholly 
under ice. He contributes a wealth of observations on old 
moraines, rows of blocks left in Alpine valleys, rock-scratches, 
scarred limestone wastes, pot-holes (Gletschermiihle\ and the 
erratics (Findltnge) irregularly scattered on the plain. A very 
valuable account was given by Agassiz of the original home, 
the course of travel, and the ultimate position assumed by 
many of the famous " erratic " blocks in Switzerland. 

Not the least interesting portion of the work is that in which 
Agassiz disposes of various erroneous explanations previously 
given for "erratics " by geologists of authority the suggestion 
of De Saussure and Von Buch that the erratics had been 
transported by river-floods, the explosion theory of Silberschlag 
and De Luc, the gliding theory of Dolomieu, and the drift 
theory of Lyell. 

After brief reference to the observations of rock-scratches 
and erratics made by Sir James Hall in Scotland, by Brong- 
niart and by Nils Sefstrom in Scandinavia, Agassiz pro- 
ceeds to enunciate his theory of the Ice Age. In conformity 
with Cuvier's Catastrophal Theory, he supposes that at the 
close of the accumulation of the geological formations 
there took place repeated falls of temperature, and that 
immediately before the Alpine upheaval the earth became 
covered with a thick crust of ice. An enormous ice-sheet 
extended over the greater part of Europe and across the 
Mediterranean as far south as the Atlas mountains, over 
Northern Asia and Northern America; above the ice-sheet 
only the highest summits emerged. 

While the Alps were being upheaved, the icy crust still 
mantled the rocks, and any fragments dismembered from the 
solid rock during the movements fell upon the ice and were 
carried away upon its surface. After the completion of Alpine 
uprise the climate became milder, and as the ice melted, great 


and small crust depressions were exposed where the rocks had 
offered least resistance to the overlying weight of ice, while 
large angular blocks were often left in undisturbed position 
upon the ground-layer of pebble and sand over which the 
ice-sheet had previously moved. 

A very short time after the appearance of Agassiz' work, 
Canon Rendu, afterwards Bishop of Annegy, wrote a paper 
on the physics of glacier ice. He attributed to glacier ice, 
in spite of its hard and brittle character, a certain ductility 
which enabled it to mould itself like plastic clay to its 
surroundings. In this conception Rendu was much in ad- 
vance of his time, as no observer had thought of any possible 
connection between plasticity and brittleness. 

In the same year, 1841, Charpentier published his Essai 
sur les Glaciers, one of the grandest contributions to the 
geology of his time. This gifted pupil of Werner, whose 
pioneer researches in the Pyrenees have already been men- 
tioned, describes in the first part of the essay the pheno- 
mena of glaciers with a fine precision, rivalling that of 
Saussure, and with a completeness far beyond any previous 
contribution on glaciers. He relies almost exclusively upon 
his own observations, whereas Agassiz frequently used the 
accounts in the literature. The second part of the essay is 
even more important. In it erratic blocks are discussed, and 
the author brings forward a convincing series of facts, from 
which he draws his conclusion that only glaciers could have 
transported the blocks and stranded them in their present 

With characteristic modesty, Charpentier claims neither for 
Venetz nor for himself the authorship of the idea that larger 
glaciers had formerly filled the Alpine valleys and had left 
the erratics strewn along them. He relates that uneducated 
mountaineers, more especially a chamois-hunter, Perraudin, 
from Lourtier, and a native of Chamonix, Marie Deville, had 
formed this idea and communicated it orally. He also recalls 
a remark of Playfair's that had long sunk into oblivion, but 
was the same in effect as Charpentier's own conclusion. 

The hypothesis of a connected ice-sheet, which had been 
propounded by Agassiz, was not accepted by Charpentier. In 
the essay, Charpentier explains his arguments against it, and 
he further insists that the maximum advance of the glaciers 
occurred after the upheaval and partial subaerial denudation 


of the Alps, and not before the upheaval, as Agassiz had 
assumed. The particular distribution of the transported 
blocks upon the slopes of the valleys, often in long lines, 
affords, in Charpentier's opinion, clear proof that river-valleys 
had already been eroded in the mountain-system before the 
glaciers made their descent to the plain. Neither does he 
agree with Agassiz that the Ice Age was the result of a 
universal fall of temperature over the earth associated with 
astronomical causes, but regards the climatic variations in the 
Alps, and the advance and greater dimensions of the glaciers, 
as local phenomena. 

Although Agassiz and Charpentier differed in their general 
conclusions, both followed the true inductive method, and the 
leading principles which they established by their study of the 
Swiss glaciers have held their place in geological literature. 
The moraines and appearances produced by them had been 
treated by Agassiz with the fullest detail and the most brilliant 
results. But between 1840 and 1845 tne glaciers themselves 
were made the chief subject of his investigation. 

Provided with physical instruments and a boring apparatus, 
he went in 1840 to the Grimsel Hospice; on the median 
moraines of the Lower Aar Glacier he erected a primitive hut, 
the "Hotel des Neuchatelois," which he occupied together 
with his companions, E. Desor, C. Vogt, F. von Pourtales, 
C. Nicolet, and H. de Coulon. Agassiz and Pourtales under- 
took the meteorological observations and the investigations on 
the inner structure and movement of the glaciers. Vogt 
studied the microscopical fauna of the red snow, Nicolet the 
flora of the neighbourhood, Desor and Coulon the glacier 
appearances and the moraines. In the following years, Escher 
von der Linth, the Scotsman J. D. Forbes, the artist Burck- 
hardt, and others, took part for a time in the work on the Aar 
glacier, and in the ascents of the Jungfrau, which were made 
under the care of the guide Leuthold. 

The researches made from the hut were the first systematic 
observations on the movement of ice in the different parts of a 
glacier under the various diurnal and seasonal conditions, 
and on the temperature of the ice at different seasons, while 
the first facts regarding the thickness and internal structure of 
the ice were secured by means of borings. 

While Agassiz and his band of enthusiastic workers were 
busy in the high levels, the lower valleys at the north and 


south base of the Alps were being examined by A. Guyot. 
Agassiz had asked him to study the former extent of the 
glaciers and the erratic blocks. The original intention was to 
publish a work in common which should comprise the results 
of all the participants in the glacier researches ; Agassiz was to 
write the first volume on the glacier phenomena proper, Guyot 
was to write the second volume on the erratic blocks in the 
Alps, and Desor was to contribute a third volume on extra- 
Alpine material. Only the first volume was ever published, 
Agassiz' Systhne Glaciaire, 1847, vv ^ tn three maps and nine 
folio plates. Guyot went to Princeton, in North America, and 
placed his 5000 samples of erratic blocks in the Museum 
there. The most important results of his researches were 
published, 1843-47, in the Bulletin de la Societe des Sc. naf. de 

When Agassiz had, in 1840, made known his Ice Age 
theory, he knew the Northern Diluvium only from the litera- 
ture. A visit to the Glasgow Meeting of the British Associa- 
tion in 1840 afforded him the opportunity of studying the 
erratics in the Scottish Highlands. Together with his former 
opponent, Buckland, whom he completely converted to his 
views, Agassiz found signs of glacier action widely distributed, 
old moraines, glacier scratches, roches moutonnees, and he 
identified in the Scottish " Till " (boulder-clay, ground- 
moraine) scratched pebbles and the fine clay and sand 
material which glaciers push forward on the ground as they 
move. The importance of the scratched pebbles as indications 
of glacial formations was thus recognised for the first time. 

In his Glacial System^ Agassiz moderated his views on a 
connected polar ice-mantle over the greater part of Europe; he 
allowed that the glaciation of the Alps had been distinct from 
that of the northern lands, and that it had taken place after, 
and not before the upheaval of the mountain-system. He 
also accepted the testimony of Rendu and Forbes on the 
plasticity of glacier-ice, and referred the movement of glaciers 
to a combination of physical causes of which dilatation was only 

The enthusiasm of the Neuchatel glacialists was infective, 
and for some years glacial studies were highly popular. The 
physicist, James Forbes, from Edinburgh, went for three 
summers in succession, 1842-44, to Switzerland to study the 
movement of glaciers. His results appeared from time to 


time in the form of letters in the Edinburgh New Philosophical 
Journal. He established the important fact that glaciers move 
more rapidly in the middle than at the sides and bottom, 
and argued from this differential motion that the glacier ice 
behaved like a slightly viscous mass, which under the influence 
of gravity was bound to flow slowly downward after the manner 
of a lava stream. So many of the glacier phenomena were 
explained by Forbes's theory of the plasticity of the ice, that it 
immediately found wide acceptance. 

The Swiss botanist, Martins, explored glaciers in Spitz- 
bergen and Scandinavia. He demonstrated the former greater 
extent of the glaciers in those territories, and made the first 
detailed study of " ground-moraines," and the kind of sedi- 
ment deposited by the river out-flows from glaciers (glacial 

In all countries where science was cultivated rapid studies 
were made between 1840 and 1850 in glacial geology; Great 
Britain, the Pyrenees, the Black Forest, Upper Italy, Scandi- 
navia, North America, were diligently and successfully searched 
for evidences of an epoch of extensive glaciation. Germany 
was much longer in accepting the new teaching. Leopold 
von Buch strongly opposed the results attained by the Swiss 
glacialists, and his influence retarded scientific inquiry of the 
question in North Germany. 

The city of Munich enjoys exceptional natural advantages 
of position for glacial research, seeing that the Bavarian plain 
upon which it stands has been smoothed and scratched by the 
ancient glaciers upon the Bavarian Alps and the Tyrol, and 
the river Isar, which flows through Munich, gives immediate 
access to the system of Alpine valleys formerly occupied by 
these glaciers. The famous astronomer, Gruithuisen, had 
published at Munich, in 1809, a paper on the erratic blocks of 
the South Bavarian plain, wherein he stated that they had been 
brought from the neighbouring Tyrolese and Bavarian Alps. 
He advanced the idea that glaciers had transported them to 
the low Alpine levels, and then the ice-masses in which the 
erratics were wedged had been borne northward across the 
plains by enormous floods, the same which had spread the 
nagelflue conglomerates over the sub-Alpine Bavarian plain. 
As the ice-masses melted, the erratics were left in their various 
positions. This was in substance the conception adopted by 
Karl Schimper several decades later. 


The North German School of Diluvial geologists looked 
with a certain favour upon this explanation, but believed still 
more in the efficacy of water action. The Berlin physicist, 
Wrede, in 1802 gave his opinion that the granite "foundling 
blocks " on the German plain had been brought upon ice-floes 
from the Silesian mountains. Leopold von Buch in 1810, and 
one or two later authors, proved, however, that Scandinavia had 
been the original home of most of the North German erratics; 
they assumed that gigantic floods had been the chief agent of 
transport, and that the scratches on the rocks and pebbles had 
been caused by the friction of the sand, pebbles, and larger 
fragments during transportation. 

Bernhardi, Professor in the Academy of Forestry in Dreis- 
sigacker, without any knowledge of the researches of Venetz 
and Charpentier, by his own insight arrived at the true solution 
of the problem (Neues Jahrb. fur Miner., 1832). He said the 
polar ice had extended to the southmost edge of the German 
plain now bestrewn with erratics, and that in the course of 
thousands of years the polar ice had gradually withdrawn to 
its present reduced dimensions and more limited fields of 
glaciation. Before Bernhardi, the Norwegian geologist, Jens 
Esmarch, in 1824 had suggested there had been a far greater 
extension of the Norwegian glaciers than now existed. But 
the tide of influence and authority in Germany at the time ran 
in other directions; an Esmarch or a Bernhardi might say 
what they thought, but there the matter ended ; none listened 
while a Von Buch and a Sefstrom said differently. The Swede, 
Nils G. Sefstrom, was the most extreme of the diluvialists. 
He taught that the northern floods had spread diluvium over 
Scandinavia, Finland, Russia, and Germany, and borne frag- 
mented rock-material and big boulders from the northern areas 
as far south as the foot of the Alps, 

During the years 1839-43, a brilliant group of British 
geologists, Lyell, De la Beche, Darwin, and Murchison, 
thoroughly acquainted with the results of the polar explorations 
made by Parry, Scoresby, and Ross, founded the "Drift Theory," 
which appeared to be a satisfactory explanation of all the 
phenomena. They attributed the transport of erratics and 
the formation of the thick surface deposits or "boulder forma- 
tions," known under various local terms in Great Britain, most 
commonly as "till," or "boulder-clay," to floating icebergs 
which had drifted far southward from Polar regions. The 


term " Drift " then came to be applied to the same deposits 
which had been previously termed "Diluvium" (ante, p. 114); 
and both terms are retained in popular use as synonyms of the 
more technical term " Pleistocene," introduced by Sir Charles 

A young Russian geologist, Bothlingk, published in 1839 a 
paper of exceptional interest descriptive of the "diluvial or 
Pleistocene deposits " in Finland and Lapland. In his opinion, 
the greater mass of the "diluvium" had virtually been de- 
posited by floods, but the erratic blocks could only have been 
transported by ice. His work helped to bring the "Drift 
Theory" into favour on the Continent, and comparatively few 
of the leading geologists in Europe at that time lent a willing 
ear to the ice theory of Swiss geologists and their conception 
of a continuous ice-sheet, or glaciers hundreds of miles long. 

The departure of Agassiz for North America in 1847 took 
away from Europe the best-known and most powerful exponent 
of glaciation, and a period of stagnation ensued in glacial 

Seven years passed, and another enthusiastic glacialist took 
the place of Agassiz in European literature. Sir Andrew 
Ramsay 1 not only proved the former glaciation of Scotland 
and Wales, but recognised traces of two Ice Ages in the con- 
stitution of the breccias and pebble-beds of Malvern and 
Abberley. He also found evidence of glacier action in the 
Permian period, and this raised anew the questions of climatic 
periodicity and ice erosion. Venetz and Morlot had been of 
opinion that during the diluvial epoch all the greater areas of 

1 Andrew Crombie Ramsay, born 1814, in Glasgow, was intended for a 
merchant's career, when, on the publication in 1841 of his excellent treatise 
on the geological formation of the island of Arran, De la Beche secured 
him as assistant for the geological survey, with which Department he was 
connected for forty years, first as survey geologist, then as local director, 
and, after Murchison's death in 1871, as General Director. At the same 
time he discharged his duties as Professor of Geology at the School of 
Mines in London. Ramsay was ranked as the best field geologist in Great 
Britain. His principal work is a geological description of North Wales, 
which appeared in two editions (1866, 1881). He also published a geo- 
logical map of England and Wales, 1859; fifth edition, 1881. Besides his 
official duties, Ramsay occupied himself much with the problems of physical 
geography and dynamical geology. His Text-book of the Physical Geology 
and Geography of Great Britain appeared in five editions between 1864 
and 1878. (Comp. Sir Arch. Geikie, Memoir of Sir Andrew Crombie 
Ramsay t London, 1895.) 


glaciation had been repeatedly covered by ice. This view now 
received more credence, especially after Oswald Heer's re- 
searches on the palaeontology of the Ice Age in Switzerland 
discovered the presence of " Interglacial " deposits containing 
the fauna and flora of a warm, temperate climate, and there- 
fore betokening a prolonged interruption of the polar con- 

After Ramsay's brilliant work had proved that almost the 
whole of Great Britain had been covered by a vast ice-sheet, 
Kjerulf and Otto Torell demonstrated that Scandinavia had 
been entirely buried under an ice-sheet some 6000 or 7000 
feet thick. In South Bavaria, topographical conditions led 
Captain Stark to suggest that the surface of the plain had been 
glaciated; and Zittel in 1874, by his discovery of good examples 
of striated rocks and his determination of typical end and 
ground moraines, established upon a scientific basis that a 
great portion of the Bavarian plain had been an ice-field. 

Still, however, the North German geologists held fast to the 
drift theory of the earlier decades of the century. It is in the 
memory of many living geologists how that theory received its 
death-blow in Berlin on the 3rd November 1875. On that 
evening, at a crowded meeting of the German Geological 
Society, Otto Torell delivered a powerful address on the course 
of glacier ice from the central ice-sheet of the Scandinavian 
plateau to the plains and basins of Northern Europe, and 
brought home to his Berlin audience with irresistible arguments 
that the erratics on the North German plain had been dis- 
persed there by glaciers moving southward. The deep impres- 
sion made by the eloquent Norwegian was never forgotten ; 
the drift theory collapsed, and the name of Bernhardi was 
recovered from oblivion to receive belated honour and be 
ranked as that of an anticipator of glacial geology. 

The German geological literature was then rapidly enriched 
by papers on glacial deposits. One of the most effective was 
contributed by Professor Penck upon the boulder-clay forma- 
tion of North Germany (Zeitschrift d. D. G. Ges,, 1879). 
Since then active researches have been continued by the 
Prussian Geological Survey Department, and it has been 
shown that there are two distinct series of glacial boulder-clay, 
separated by interglacial layers containing remains of a rich 

Professor Penck in 1882 published a work entitled The 


Glaciation of the German AIps> which has become a classic in 
the literature. The careful inquiries conducted by Alphonse 
Favre and Desor, and the more recent works of Heim, Du 
Pasquier, and Bruckner, meantime advanced the knowledge of 
topographical and geological phenomena due to the glaciation 
of the Swiss Alps, while similar studies have been carried on 
by many eminent geologists in the countries of Northern 
Europe. In Great Britain, Sir Henry Howorth, Professor 
Hull, and Professor Bonney still support Lyell's "drift 
theory " , the majority of British geologists, however, have 
accepted the ice theory, of which Sir Andrew Ramsay, Sir 
Archibald Geikie, and Professor James Geikie have been the 
ablest exponents. 

The exploration of existing masses of inland ice and of the 
glaciers in the high mountain-systems exerted a stronger fascina- 
tion for many than the study of the deposits of the past Ice 
Age. Dr. Simony, a Viennese enthusiast, has taken accurate 
observations for more than forty years on the Dachstein glacier, 
and Pfaff has studied the glaciers of the Gross Glockner, in 
the Austrian Alps ; in Switzerland, a scientific society has been 
founded for the pursuit of glacier research, and measurements 
on the Rhone glacier have been taken for many years. 

Amund Helland's observations on the comparatively rapid 
movement of the glaciers at Jacobshavn surprised European 
scientists, whose ideas of glaciers had been formed mainly on 
the basis of Alpine glaciers. Nordenskiold's travels, Fridtjof 
Nansen's bold crossing of the Greenland ice, Keilhack's and 
Von Drygalski's careful physical and mathematical geological 
observations on the glaciers and ice-fields of Iceland and 
Greenland, confirmed with irrefutable data the action of inland 
ice-masses and the correctness of Torell's explanation of the 
"diluvial" phenomena in Northern Europe. The boldness, 
the enthusiasm, and the achievements of these explorers 
have worked inspiringly on the public mind, and awakened 
an interest in the scientific aspects of Arctic territories 
which finds an outlet in the warm support given to the 
geographical societies in all countries and to the schemes for 
further exploration that are from time to time initiated. 

As has been said, Charpentier recognised the work of 
denudation affected by glaciers, but much broader views of the 
erosive power of ice were formulated by Gabriel de Mortillet in 
several papers published between the years 1858 and 1862. 


Ramsay then wrote a general paper " On the Glacial Origin of 
certain Lakes in Switzerland, the Black Forest, Great Britain, 
Sweden, North America, and elsewhere" (Q. 'Jour, GeoL Soc., 
1862). In this paper Ramsay attributed the excavation of 
many lakes and fiords to the erosive force of moving ice, and 
Tyndall in the same year gave his opinion that the Alpine 
valleys had been excavated by the same agency. 

During the forty years that have elapsed since that time the 
erosive force of ice has been a subject of animated discussion, 
and still there are two distinct parties amongst glacialists, 
those who oppose and those who support the main issues of 
Ramsay's discourses. Amongst the supporters or extreme 
glacialists may be counted in Great Britain such geologists of 
authority as Sir Archibald Geikie and Professor James 
Geikie; in Austria, the geographer and geologist, Professor 
Penck; in Switzerland, Professor Briickner; in Scandinavia, 
Professor Nansen ; while in North America Sir William Logan 
was a warm supporter. 

Geologists who oppose the extreme view of glacial erosion 
have pointed out that a variety of local causes may give origin 
to lakes and fiords. Actual cases have been cited where 
fluviatile, or morainic accumulations, or, crust movements 
would sufficiently explain the form of the basins attributed 
to ice erosion. 

Much has been written in physics upon the causes of ice 
movement. Of great importance were the experiments made 
by Carnot and James Thomson (1849) on the liquefaction of 
ice under strong pressure, and the lowering of the melting 
point below o, as well as the discovery made by Faraday 
(1850) of the re-union or regelation of fragments of ice with 
moist surfaces. Application of the principle of fragmentation 
and regelation to the phenomena of glaciers was made by the 
leading physicists of the day, Tyndall (1857), Helmholtz 
(1865), and Lord Kelvin, and thus a scientific explanation 
was secured for the theory of glacier motion which had been 
originally advanced by Rendu and Forbes. Professor Heim, 
in his excellent Handbook of Glacier Phenomena (1885), 
summarises the whole field of knowledge of Alpine glaciers. 
He decides the question of glacier motion in the main in 
favour of Forbes's theory of plasticity, but he also recognises a 
gliding movement of the whole mass under the influence of 


Numerous observations in different areas have testified to 
the frequent oscillations of the glaciers during the Ice Age. 
The glaciers appeared to have frequently retired, and ice-fields 
to have diminished in size as often as any amelioration in 
climatic conditions set in. Such variations may be observed 
in ice-clad regions at the present day. And as the lique- 
faction of the ice-masses gives rise to larger volumes of water, 
the frequent local floods, of which evidences are afforded in 
the intercalation of fluvio glacial deposits within the glacial 
series, are thought to have been associated with periodic 

Two main advances of the mountain glaciers and of inland 
ice were determined by Ramsay for the British Isles and by 
Heer for the Alps, and have been confirmed by Scandinavian 
and German geologists upon the evidence of the glacial and 
fluvio-glacial deposits in their respective countries. In all 
these areas a prolonged interlude of milder climatic conditions 
appears to have intervened between two chief epochs of 
glaciation. But Professor Penck in recent papers has aug- 
mented the number of distinct epochs of glaciation in the 
Alps and North Germany to three or four, thus approaching 
the " five " glacial intervals enumerated by Professor James 
Geikie, and the "seven" by James Croll. On the other 
hand, Hoist in Norway, Upham and Wright in North America, 
and many other authorities recognise only one Ice Age, marked 
by occasional seasonal or periodic variations of no great 
significance in the dimensions of the glaciers and inland ice. 

It is still more doubtful whether geologists have been right 
in supposing that several Ice Ages occurred during geological 
epochs previous to the Diluvial Age. Ramsay, in 1855, 
explained certain Permian conglomerates in England as 
accumulations transported by glacial action, and Dr. Blanford 
applied a similar explanation in 1856 to the "Talchir" con- 
glomerates of almost the same geological age in Central and 
Southern India. It then became commonly accepted that 
extensive glaciation had occurred in the Permian geological 
epoch. Erratics and scratched pebbles have since been 
described from the Silurian rocks in the southern counties of 
Scotland by Moore and James Geikie, and also in the Old 
Red Sandstones or Devonian rocks of Scotland by Ramsay. 

The Miocene conglomerates in the neighbourhood of Turin 
were explained by Ramsay, Lyell, and Gastaldi as material 


transported by ice, and a similar explanation was suggested 
for the exotic blocks in the Alpine and Carpathian " Flysch " 
formation. From time to time examples of boulder and 
conglomerate deposits were reported and were dealt with in 
this way. To mention a few examples: in 1870 Sutherland 
described breccias with polished blocks in the Karroo Beds of 
South Africa, and in his explanation of them as glacial in 
origin he was supported by Griesbach (1871) and Stapff 
(1899); in Australia, R. D. Oldham explained boulder con- 
glomerates in Carboniferous and Permian time as material 
transported and stranded by icebergs; Waagen (1887) de- 
scribed scratched pebbles and polished blocks from the Salt 
Range in the Punjab, and referred them to a Carboniferous 
Ice Age; Notling more recently (1896) concludes they belong 
to a Permian Ice Age ; Sir A. Geikie mentioned glacial traces 
in the Cambrian rocks of Scotland, and Reusch (1891) in the 
Cambrian deposits of Northern Norway. The conclusion 
drawn by James Geikie and James Croll is that all the greater 
epochs in the history of the earth have been marked by a 
series of glacial and interglacial episodes. 

But the number of geologists who accept the teaching of 
repeated glaciation of wide territories is rather decreasing than 
increasing. The minute detail in which geological maps are 
now being prepared tends to show that in many cases all these 
phenomena of scratched pebbles, and boulders, and polished 
surfaces may be observed in the sheared and brecciated rock- 
material occurring along the planes of great crust-movements. 
And in no case will a cautious geologist be willing to accept 
an ice age, or even local glacial action, in a remote geological 
epoch as the explanation of scratched pebbles and the occur- 
rence of exotic boulders, unless he be in a position to investigate 
the matter for himself, or it can be conclusively proved to him 
that there has been no history of crust-disturbance. The 
attitude of present-day geology with respect to the much 
vexed questions of glacial action is to hold an open mind 
towards each alleged example. 

The Pleistocene ice-mantle had its chief distribution in the 
north-west of Europe and in the north-east of America ; but, 
with the exception of those large areas covered by inland ice, 
the evidence of glaciers is found only in mountain ranges 
which still possess glaciers, or in which a very slight climatic 
depression would call forth glaciers. Hence the glaciation 


during the Pleistocene Age is most simply regarded as repre- 
senting an extreme phase of existing climatic conditions. 

Charpentier thought at first that the glaciation might have 
been due to the former greater height of the Alpine system ; 
but he afterwards modified his opinion in so far as he regarded 
an exceptionally high rainfall in addition to a low temperature 
as a necessary condition in the accumulation of immense 
masses of ice. Charpentier argued that the atmosphere must 
have been loaded with moisture, which became condensed 
over the high Alpine regions. 

Many attempts have been made to explain the Pleistocene 
climate, sometimes cosmic causes, sometimes telluric causes 
being selected as the more important. Sir Charles Lyell 
ascribed the climates of geological epochs solely to telluric 
influences (ante^ p. 192). He thought the Ice Age in Europe 
and North America was explicable upon some such assump- 
tion as a close grouping of islands round the North Pole, a 
heightening of the continental territories between 70 and 80 
latitude, a submergence of the temperate zone below the 
ocean, and a diversion of the warmth-giving Gulf Stream. 
Escher von der Linth and Desor brought forward (1863) in 
support of this theory their conclusion that the Sahara had 
been totally submerged during Pleistocene time, and that the 
consequent absence of the warm Fohn wind must have lowered 
the temperature of Central and Southern Europe. It has since 
been shown by Dove that the Fohn wind -does not come from 
the Sahara, and Zittel and other scientific explorers of the 
Sahara have disproved the old idea that the Sahara was under 
water during the Pleistocene age. 

The principle involved in LyelPs theory was accepted by 
Sartorius von Waltershausen and Stanislas Meunier, who 
assumed a much greater height and breadth of the mountain- 
systems as the chief modifying cause. Meunier showed that 
the accumulation of snow and ice on extensive mountain 
plateaux would of necessity lower the temperature. The 
Norwegian geologist, K. Pettersen, believed that an Arctic 
continent existed between Greenland and Spitzbergen during 
the Ice Age. 

The explanations which have received the widest recognition 
are, however, based upon cosmic causes. The French mathe- 
matician, Adhe'mar, in 1832 contributed a remarkable paper 
on the "Revolution of the Sea: Periodic Deluges." He 


drew attention to the eccentricity of the earth's orbit round 
the sun, and the fact that during the summer season of the 
southern hemisphere the earth is in its nearest position to the 
sun (perihelion), while during the winter season of the same 
hemisphere the earth is at its greatest distance from the sun 
(aphelion). He then argued, since the eccentricity of the 
orbit was variable, sometimes having the form of a long 
ellipse, sometimes approximating to a circle, during the epochs 
of greater eccentricity of the orbit, the hemisphere whose 
winter falls in aphelion would undergo a protracted period of 
winter cold. The climate might be thereby rendered so severe 
that stupendous masses of ice would accumulate near the Pole 
in aphelion, and as a further consequence the centre of gravity 
of the earth might be shifted. According to Adhemar, the 
conditions favourable for extensive glaciation recur in each 
hemisphere at intervals of 10,500 years, and thus call forth 
periodic Ice Ages. 

Although Sir John Herschel, Arago, and Humboldt were of 
opinion that the eccentricity of the earth's orbit could have but 
a slight influence upon the climate of our planet, Adhemar's 
theory was accepted by Julien (1860) and Le Hon (1868) 
with scarcely any modification. James Croll treated the 
subject of cosmic causes of climatic variation in a memorable 
work, Climate and Time (1875). He improved the theory 
enunciated by Adhemar, inasmuch as he showed the depend- 
ence of the prevailing winds and ocean-currents upon the 
eccentricity of the earth's orbit, and explained how masses of 
ice and snow accumulating at the Pole must, in virtue of their 
radiation of cold, absorption of heat, and condensation of 
moisture, tend strongly to reduce the temperature. Croll 
supposed that the interglacial periods were characterised by 
the almost complete withdrawal of the glacier ice, and by 
extensive subaerial disturbance of the glacial deposits. In 
Great Britain, Croll's views have been accepted by many 
geologists, amongst others by Sir Archibald Geikie and his 
brother, Professor Geikie. Professor Penck and Professor 
Pilar are the best known of Croll's adherents on the 

Sir Charles Lyell took objection to Croll's theory, mainly 
because of the insufficient geological evidence of recurring 
epochs of glaciation; nor can this objection be said to be even 
yet overcome. Neumayr doubts, on the one hand, whether 


variations of eccentricity could affect climate to such an extent, 
and on the other, he thinks CrolPs whole chain of argument 
valueless, since, excellent as it is, astronomy has Jiot yet ascer- 
tained with any security that there have been periods of very 
great eccentricity of the orbit. Poisson (1837) suggested that 
climatic variations might result from movement of the solar 
system through warmer and colder portions of space; other 
authors have suggested changes in the obliquity of the ecliptic 
or a shifting of the earth's axis as possible causes of variation, 
but science has not yet arrived at any generally accepted 
solution of the difficult climatic problem of the Ice Age. 

D. Geological Action of Organisms. Scientific research has 
abundantly shown how subtle is the chemistry of life, and how 
important and complex is the part played by the organic world 
in the economy of nature. 

Plants and animals abstract from the atmosphere, from the 
soil and the rocks, certain inorganic constituents which enter 
into new chemical combinations in the active tissues of the 
living organisms, and are partly assimilated, partly returned in 
altered form to the atmosphere and the ground. 

Animal creation thus serves as an intermediary between the 
atmosphere and the earth's surface, utilising and metabolising 
matter derived from both, and effecting transferences from the 
one to the other. 

The present action of living organisms upon the earth's 
surface is therefore partially to destroy, partially to renew and 
enrich it; and similar functions were fulfilled by living organ- 
isms in past ages. But more important for geology than the 
changes effected by metabolism and mineral decomposition 
is the consideration of the additions made to rock-deposits by 
the accumulation of organic remains. 

The destructive effects of plant-growth are produced in virtue 
both of chemical and mechanical agencies. When plants 
decay, organic acids develop, and, as Bischof and more 
recently Julien have shown, these have a strong solvent and 
oxidising action upon the surrounding mineral matter. More 
especially when combined with water they promote rapid 
decomposition of the rocks, and their disintegrating action, 
productive of soil, may be traced to considerable depths below 
the surface. The roots of plants as they penetrate downward 
through the rock-fissures exert a certain mechanical force upon 


the rocks. Even the rootlets of grass and other vegetation 
bore their way through sub-soil, and thus prepare an easier 
path for the infiltration of surface water and its combination 
with the organic acids as it proceeds on its subterranean 
passage. While, therefore, a thick covering of vegetation 
helps to protect the ground from sudden landslips and rapid 
surface denudation, and has a beneficent influence upon 
climate, the decay of vegetation slowly and surely rots any 
mineral matter within reach of the powerful humus acids. 

Peat-mosses occupy wide areas in the Temperate and Arctic 
zones, and have been frequently made the subject of scientific 
researches. In 1810, Rennie published his work, Essays on 
Peat-Moss, an able treatise on the Scottish peat-mosses; and 
the nature and origin of peat-deposits were afterwards eluci- 
dated in handbooks by Dau (1823) and Wiegmann (1837). 
What Rennie achieved for the Scottish peat-mosses, was done 
for the Danish and North German peat-deposits by Steenstrup 
(1841) and Griesebach (1845). These authors defined for the 
first time the differences between Sphagnum mosses char- 
acteristic of marshes on mountain-slopes and valleys; low- 
lying or lacustrine growths and deposits of peat rich in rushes 
and sedges; and forest-peat or swamps. A typical example of 
a forest moss is the " Dismal Swamp " in Virginia, which Lyell 
described in 1841, and Lesquereux afterwards examined in 
more detail. 

Modern deep-sea researches have discovered a few instances 
of marine peat; and according to the new investigations of 
Eugene Bertrand, isolated coal-beds occur which have been 
mainly formed by sea-weeds, for example the " Boghead " coal, 
near Autun, and the "Kerosene" in Australia. The low 
coasts, estuaries, and river-mouths in tropical lands are fre- 
quently fringed by mangrove-trees whose withered roots and 
fallen radicles form coaly deposits on the sea-floor, mixed with 
a large proportion of the finer coastal detritus. In a similar 
way, drift-wood may accumulate in large rivers, and by the 
process of subaqueous decay may be converted into lignite, 
or a substance of the nature of brown-coal. Lyell's descrip- 
tion of the "rafts" of the Mississippi will be familiar to most 

Fossil brown-coal may be compared with these recent forma- 
tions. The origin of brown-coal from plant-decay has never 
been questioned. A valuable monograph on brown-coal, describ- 


ing its physical and chemical constitution, its palaeontology, 
geological occurrence, and geographical distribution, was pub- 
lished by C. F. Zincken in 1865. 

Fossil peat-deposits occur, so far as at present known, only 
in the post-Tertiary or Quaternary formation. The black- 
coal deposits of the old formations were frequently compared 
in geological literature with brown-coal, but the homogeneous 
structure and the rarity of good plant-remains in black coal, 
threw great doubt upon this explanation of its origin. Agricola, 
in 1544, explained it as condensed petroleum, and his opinion 
still found favour with Voigt in his special work on Coal- 
deposits (1802) and with Buckland (1822). 

Kirwan, the opponent of Hutton, even explained coal as a 
product of the chemical decomposition of Archaean rock, while 
Andreas Wagner supposed it to represent condensed and de- 
oxidised carbonic acid derived from an atmosphere super- 
saturated with carbon dioxide. Many of the geologists in the 
eighteenth century upheld the correct explanation; amongst 
others Scheuchzer in 1706, Beroldingen in his work on Contro- 
versial Points in Mineralogy (1778), and James Hutton in 
Great Britain (1785). But it was not until the microscope 
was applied to its investigation that the origin of coal from 
plant-growth in situ was securely established. In 1848, the 
German botanist, Dr. Heinrich Goeppert, proved that the 
vascular cryptogams and conifers whose remains accompany 
coal-formations had supplied the material of the deposit. 
His results were corroborated by Dawson in 1859; but 
even after this date erroneous conceptions from time to 
time were advanced with regard to the kinds of vegetation 
which had given origin to the coal-deposits. A decisive 
paper on the subject was contributed by Giimbel to the 
Bavarian Academy of Sciences in 1883, wherein he gave 
microscopic sections showing the fine textures of the various 
plant-remains in peat, brown coal, black coal, and anthracite. 

The transformation of decayed plant-remains into coal takes 
place under the fundamental condition of limited access of 
air, and is promoted by heat and pressure. There is little 
doubt that all three factors have contributed to the origin of 
the deposits of black coal, and Bischof suggested that the 
characteristic chemical and physical constitution of the 
varieties of coal had been determined by definite relations in 
the amount of air admitted and in the accompanying heat and 



pressure. A considerable loss of substance takes place during 
the transformation ; Bischof reckoned that a mass of plant 
material about eighty feet thick will only yield a coal-seam 
about three feet in thickness. 

There still continues a difference of opinion whether black 
coal originated in situ or if the plant material had been drifted and 
deposited in the same way as other sedimentary rock. Lyell, 
Logan, Goeppert, Giimbel are among the geologists who sup- 
ported the view that the transformation of the vegetable matter 
took place in situ, as in the case of the large proportion of 
peat-mosses, and this is the common opinion of geologists. 

In France, however, the theory of sedimentation is strongly 
supported. Grand-Eury, the author of an excellent work pub- 
lished in 1882, upon the flora of the Carboniferous formation 
of Central France, came to the conclusion that the coal-seams 
had originated by deposition in lake-depressions surrounded 
by woods. Five years later, the Etudes of Henry Fayol 
on the Coal-deposits of Commentry brought forward a strong 
chain of evidence in favour of sedimentation from water. 
Fayol shows how the pebbles, sand, mud, and plant detritus 
borne in suspension by rivers subside according to their weight, 
and arrange themselves as independent layers of sediment. 
The coarser pebbles are deposited near the shore, usually with 
a distinct slope, while the light plant detritus is carried far out 
and deposited almost horizontally. 

In accordance with the amount of rainfall, the volume 
and velocity of the inflowing water vary, likewise the erosive 
action of rain and river water and the quality of the sediments. 
So that the alternation of conglomerate, sandstone, shale, and 
coal-seams observed in most coal-basins finds, according to 
Fayol, a natural explanation upon the basis of increase and 
decrease of rainfall without assuming oscillations of ground- 
level as has been done by the supporters of the coal-swamp 
theory of origin. 

De Lapparerit has not only. accepted the views of Fayol and 
applied them generally to coal-basins, but also supported them 
by further arguments. It is in no small measure due to the 
prestige of this gifted geologist that the sedimentation theory 
is held by the majority of French geologists at the present 
day. A slight modification of the theory was recently advanced 
by Ochsenius (1892), who suggests that river-bars controlled 
the admission of the inflowing water into the lake-basins, 


When the river-water was low, only the most buoyant plant 
detritus could be floated across the bar ; when the water level 
was high, sand and pebbles were also carried into the basin of 
deposit (ante, p 220). 

Lake-deposits of siliceous earth ("kieselguhr") were dis- 
covered by Ehrenberg in 1837 to be composed of 
the silicified valves or fragments of valves belonging to 
unicellular plants of microscopic size, the Diatomacese. 
These plants exist both in fresh and salt water, and their 
remains have gathered on the floor both of inland lakes and 
the ocean. Ehrenberg first demonstrated the presence of 
diatom remains in the ground of Berlin, in the peat-mosses 
of the Liineburg heath, afterwards in samples of pelagic 
deposits, and in the "kieselguhr" and "tripoli powder" of 
Bilin in Bohemia, Richmond in Virginia, and other places. 
The explorations of the Challenger Expedition proved that 
extensive areas of the ocean-floor were covered by the skeletons 
and fragmentary debris of diatoms. In 1889, Weed found that 
the separation of silica from the hot springs and geysers of 
the Yellowstone Park was largely accomplished by diatoms. 

More important is the assistance rendered by certain plants 
to the elaboration of limestone. It has long been known that 
the formation of calcareous tufa is promoted by the growth of 
moss, rushes, and certain algae. On the other hand, it was 
discovered comparatively late in the history of research that 
marine limestones sometimes attaining great thicknesses owe 
their origin to algal organisms. Philippi was the first to 
recognise, in 1837, that the pelagic Nullipores previously 
regarded as polyps or Bryozoa belonged to the group of Cal- 
careous Algae. The name of Nullipores was changed to Litho- 
thamnia and Melobesia, and Unger in 1858 demonstrated the 
important part such organisms had played in the construction 
of the Leitha limestone in the Vienna basin during the 
Miocene period. Two important works on the subject were 
contributed and laid before the Bavarian Academy of Sciences 
by Giimbel in 1871 and 1872. These works not only added 
to the microscopic knowledge of the skeletal structures of the 
Lithothamnian group, but also proved that other skeletal 
remains widely distributed in the Alpine limestones, and 
which had been referred by Schafhautl to the Bryozoa under 
the name of Diplopores, agreed with the structure of the 


Charpentier had previously included Dactylopores amongst 
the Foraminifera, and the name of Foraminiferal limestone 
rapidly began to be applied to the Alpine deposits in 
question. Meunier-Chalmas, however, showed in 1877 that 
the so-called Dactylopores were not Foraminifera and did not 
belong to the animal kingdom at all, but were Calcareous Algae. 
In view of Giimbel's results, these algal organisms, under 
the new name of Gyroporella, were raised to a place of the 
first importance in the history of Alpine rock-building, since 
their aggregated remains form a very great portion of the 
enormous thickness of limestone and dolomite which adorn 
the Eastern Alps. 

In his work on Chemical Geology, Bischof had expressed 
his opinion that the thick deposits of marine limestone occur- 
ring in the geological formations had been formed by pelagic 
faunas which derived the calcareous substance from the calcium 
carbonate in sea-water. Volger in 1857 showed that the 
source of the lime was for the most part not the very small 
proportion of lime carbonate dissolved in sea-water, but the 
gypsum or lime sulphate. Recent researches support Volger's 
results, and enter in more detail into the chemical processes 
by which the animal tissues are enabled t,o assimilate the lime 
as a carbonate, and to throw off the sulphur in chemical com- 
binations with waste products, more especially ammonia. 

The "tests" or "casings" of pelagic Foraminifera are some- 
times calcareous, sometimes arenaceous, and are sometimes 
imperforate (e.g. Miliolina, Orbitolites), sometimes provided 
with a number of small apertures or foramina (e.g. Nodosaria, 
Globigerina, Rotalia). 

D'Orbigny in 1825 examined both recent and fossil speci- 
mens of Foraminifera, and misled by the elaborate appearance 
of the shells, he placed them in affinity with the Nautiloid 
group of Molluscs, but since then the microscopic study of Fora- 
minifera and the extended means of comparison with related 
forms of lowly animal life have shown this group to belong to 
the Protozoa (Subd. Reticularia, Carp.); from geological, geo- 
graphical, and zoological sides of research, abundant evidence 
has been given of the pre-eminence of testaceous material in 
pelagic deposits. 

As early as 1839, Ehrenberg proved that chalk rocks were 
composed of fossil Foraminifera, and demonstrated a similar 
aggregation of minute calcareous shells belonging to recent 


Foraminifera in certain fresh samples of ocean deposit. But 
it was not until 1871, by means of the Challenger Expedition, 
that any approximate estimate of the composition of typical 
pelagic oozes could be formed. The report by Murray and 
Renard (1891) on deep-sea deposits discloses the great import- 
ance of Globigerina ooze, which covers the floor, more espe- 
cially of the central portions, of the Pacific Ocean, and is 
found at depths as great as 2,600 fathoms. It is more widely 
distributed than any of the other organic ocean muds, the 
Pteropod calcareous ooze, the siliceous ooze composed of 
diatomaceous material, or the Radiolarian siliceous ooze which 
is limited to very great depths of the ocean-floor. Littoral 
deposits are more mixed in character, usually comprising 
Molluscan, Bryozoan, and Echinoderman remains, although 
occasionally beds of individual types occur. Recent littoral 
deposits, on account of their more accessible position and the 
larger size of the faunas, have long been familiar to scientific 
observers, and were the first to be compared with fossil faunas 
in the rocks. 

The activity of reef-building coral zoophytes has been one 
of the most interesting themes in modern scientific research. 
The red coral of the Mediterranean Sea was highly prized by 
the nations of antiquity for its beauty, and has always been an 
article of commercial importance. The first mention of the 
coral growths in the Red Sea was by the Portuguese writer, 
Don Juan de Castro; in 1616, Pyrard described the coral 
atolls of the Maldive Islands; and in 1742, Peter Forskal by 
a series of investigations on coral reefs determined that the 
calcareous material for their construction was separated from 
sea-water by a small sedentary polyp. The closer study of 
the coral animal has shown it to be an ally of the Sea- 
Anemone or Actinian polyp, from which it is distinguished by 
its habit of growing as colonies, and of building up calcareous 
skeletal supports for the soft fleshy parts. 

Geology has contributed 'a vast store of information about 
the skeletal structures of reef-building corals in past geological 
epochs, and at the present day few questions are of such 
common interest to the various branches of natural science as 
those concerning corals the determination of the present 
geographical distribution of coral reefs, the climatic and 
physical conditions of growth, the chemical transformations 
undergone by the skeletal structures after withdrawal of the 


polyp, the thicknesses and areal dimensions attained in virtue 
of the continued upward growth and seaward extension of the 
reef, and the proportion of coral formations in the limestone 
and dolomite rocks of the Alps and other regions. 

Reinhold Forster, who accompanied Captain Cook on his 
voyage round the world in 1778, expressed the view that the 
formation of coral reefs was limited to the seas of warm 
climates, and wrote as follows regarding the mode of construc- 
tion : " The reef is built up by the lithophyte worms from the 
ocean-floor until it comes within a very small distance of the 
surface of the ocean. The waves wash against this newly-built 
wall all kinds of debris, mussel shells, fronds of sea-weed, 
fragments of coral, sand, and other material, so that the sub- 
marine coral wall gradually increases in height, and begins to 
be seen above the surface." 

The circular form of atoll reefs is explained by Forster as 
the result of a continued effort on the part of coral polyps to 
erect a wall protecting them from dominating winds. James 
Cook added a number of observations on reef-growth, supple- 
mentary to those of Forster; and John Barrow in 1806 made 
the first attempt to determine the thickness of coral rock on 
an island. Flinders prepared in 1801 a map of the reefs off 
the Australian coast, and in 1814 published an important 
cartographical work, in which he agreed with Forster's views 
on reef-growth. Peron in 1816 enumerated 245 islands of 
reef-coral, and determined their geographical position between 
34 north and south latitude. 

Valuable observations were made on the conditions favour- 
able for the growth of reef structures by Chamisso and Esch- 
holz, who accompanied Kotzebue's voyage of exploration 
(1814-18) in the southern seas. Adalbert von Chamisso, 
during a prolonged sojourn on an atoll of the Radack group, 
took accurate measurements, upon the basis of which he after- 
wards sub-divided coral reefs into three classes, coastal reefs, 
inland groups, and atolls. Atolls were described as circular or 
ring islands, rising like table mountains from the ocean depths 
and only showing a narrow edge above the water. Chamisso 
distinguished very emphatically the higher side of a reef 
directed towards the prevailing wind from the lower protected 
side, which is frequently interrupted, and through which a 
channel leads into the central lagoon of the island. 

He doubted whether the calcareous rock-material of the reef 


represented coral structures in their actual original position, 
and inclined rather to regard it as a stratified accumulation of 
coral debris^ embedding sometimes larger masses of coral 
colonial growths. Chamisso followed Forster in supposing 
that the coral reefs began to take shape on the ocean-floor at 
considerable depths, and their own continued growth brought 
them ultimately up to the surface. At the same time, from the 
distribution of coral islands, Chamisso thought it probable 
that corals settled upon submarine ridges. Eschholz associ- 
ated the form of the coral islands with the pre-existing form of 
submarine mountains, whose summits they crown. He ex- 
plained the origin of atolls on the assumption that when a reef 
has arrived at considerable dimensions the corals flourish best 
on the outer edge under the constant wash of the breakers 
and surf, and the reef tends therefore to increase more rapidly 
there ; the lagoon, which is seldom over 30 fathoms deep, in 
the opinion of Eschholz, arises from the decrease and even 
cessation of coral growth in the middle of the reef, where the 
refuse of molluscan shells and coral fragments accumulates 
and militates against the proper nourishment of the corals. 

Immediately following the results of the Kotzebue Expedi- 
tion, those of the Freycinet Expedition in the years 1818-20 
became known. Quoy and Gaimard published their observa- 
tions on the mode of life of reef-corals in the Annales des 
Sciences naturelles in 1825. They never found living reef- 
corals in greater depths than 25-30 feet, and therefore con- 
cluded that these polyps could only exist in shallow and warm 
water, and preferentially in protected bays little affected by 
storms. Judging also from the small thickness of the raised 
coral limestones at Timor, Ile-de-France, New Guinea, and 
the Sandwich Isles, they argued that coral reefs could never 
be very thick. In confirmation of this result they mentioned 
how frequently coral reefs occur in a direction continuing 
that of the mountain-chains on land, while the massive reefs 
are limited to submarine platforms sloping gently from the 

Henrik Steffens in 1822 suggested that coral atolls formed 
on the summit of submarine volcanoes around the crater of 
eruption, which was afterwards occupied by the central lagoon 
of the reef. The same hypothesis was advanced indepen- 
dently by Quoy and Gaimard, and during the Duperry Expedi- 
tion of 1828 was more closely investigated and accepted by 


Lesson and Garnot. The English navigator, Captain Beechey, 
took a number of soundings round the edges of coral reefs, 
and also arrived at the conviction that they were based upon 
submarine mountains, whose summits were never covered by 
more than 400-500 feet of water. 

The considerable size of many atolls made it seem some- 
what improbable that they had been erected upon isolated 
volcanoes, and this theory was opposed by Ainsworth in 1831. 
He thought that, in addition to the coral polyps in shallow 
waters, there might be certain species whose habitat was at 
greater depths. In explanation of the higher edge on the 
windward side of an atoll, he called oceanic currents to his 
assistance, and thought they compelled the polyps to build 
vertically, whereas on the leeward side nothing prevented them 
from extending the reef in horizontal direction. Charles Lyell 
was favourably inclined to the theory of a volcanic basis, but 
also stated in the first edition of the Principles that the 
inequality in the height of the atoll edges might be due to 
local variation of level, more particularly to local subsidences 
after earthquakes. 

The famous memoir by Ehrenberg, " On the Structure and 
Form of the Coral Growths in the Red Sea," published in 1834 
in the Abhandlungen of the Berlin Academy, represented the 
result of eighteen months' study in the particular localities. 
The treatise begins with an exhaustive historical account of 
the previous literature on reef-building corals and reef-forms. 
Ehrenberg then describes the form of the reefs in the Red Sea 
as ribbon-like submarine banks extending parallel with the 
coast-line, based upon gentle beach-slopes, and having their 
water surfaces about \-2 fathoms below the water-level at high 
tide. There are no exposed reef-surfaces in the Red Sea, and 
the outer side of the reef has a steep cliff edge descending 
rapidly into greater depths. The rock underlying the reefs is 
either a porous limestone or volcanic nfaterial; the coral lime- 
stone itself forms only a thin surface layer about i J fathoms thick 
upon the basal rock. Hence Ehrenberg regards the corals not 
as the builders of new islands, but only as the preservers of 
islands already existing. 

The German zoologist agrees with Quoy and Gaimard on 
one of the leading points of controversy, namely, the small 
thickness of coral structures, and confirtns their conclusion 
that the polyps can only exist in warm water not more than six 


fathoms in depth. He accepts also the theory of a volcanic 
basis as the best explanation of atolls. The accuracy and 
completeness of Ehrenberg's researches in the Red Sea have 
been since confirmed by some of the best German authorities 
on coral life Haeckel, Klunzinger, Walther. 

The reefs of the Bermuda Islands were described by Nelson 
in 1837, and this author demonstrates reef-growth upon a rock- 
basis neither volcanic nor even firm and compact; in his 
conclusions regarding the origin of atolls he supports Ains- 
worth's views. 

One of the most attractive books of the nineteenth century 
was undoubtedly Charles Darwin's great work, The Structure 
and Distribution of Coral Reefs, published in 1842. Ehren- 
berg's work had paved the way for broader conceptions about 
coral reefs; in it the barrier reef, which had in the older litera- 
ture been kept in the background by the more aggressive 
features of the atoll, for the first time received its meed of 
attention. The balance of scientific knowledge regarding the 
barrier and the atoll was now fairly equal, and Charles Lyell's 
indication of possible modifications that might ensue in the 
reef-form under the influence of differential crust-movements 
also lay open in the recent literature when Darwin's master- 
mind came to the formidable task of considering all the known 
data and constructing a scientific generalisation. 

Charles Darwin, while a member of the Beagle Expedition 
between 1832 and 1834, examined a large number of coral 
reefs, atolls, and volcanic islands in the Pacific Ocean, and 
described them with remarkable method and clearness. He 
classified coral structures in three groups, now universally 
accepted atolls or lagoon reefs, barrier reefs, and fringing 
reefs. This special work contains a map of the geographical 
distribution of the coral reefs, and enriches our knowledge by 
a wealth* of new observations on the mode of life of the corals, 
as well as on the relative part taken by the various coral types 
in the construction of the reefs. 

Darwin confirmed the fact that reef-corals only live at small 
depths and in tropical areas, and proposed upon the basis of 
crust subsidence an ingenious theory of reef-growth which 
connected the three chief varieties of reefs by intermediate 
stages. Darwin's theory assumes that every atoll reef was 
originally the fringing reef of some island, but owing to the 
subsidence of the ocean-floor, the fringing reef was gradually 


converted into a barrier reef, and finally, by continued subsi- 
dence of the floor, passed into the form of an atoll. The 
essential feature is a certain reciprocity between the secular 
movement of subsidence and the vertical or horizontal growth 
of the reef. Darwin brings the movements of the area of 
subsidence in the Pacific Ocean into correlation with the 
volcanic phenomena so widely extended in that ocean. Where 
fringing reefs still occur, he supposes that instead of subsidence, 
local elevation is taking place. The presence of barrier reefs 
and atolls, on the contrary, indicates a submergence of islands 
and a subsidence of the sea-floor. 

The distinguished American geologist and zoologist, Dana, 
had abundant opportunity during the Wilkes Expedition 
(1839-41) of investigating coral reefs, and he accepted Darwin's 
theory on all the essential points. The apparent naturalness 
of Darwin's theory recommended it to all, and in 1860 it 
seemed to find striking confirmation from the geological side. 
In that year Ferdinand von Richthofen published his account 
of the geology of Predazzo, St. Cassian, and adjacent localities 
in the South Tyrol Dolomites. He described the limited 
local occurrence of dolomite or dolomite limestone cliffs, in 
many places 2000-3000 feet thick, -and the varying age of the 
sedimentary deposits at the base of the cliffs. These were 
sometimes the tufaceous Wengen strata, sometimes richly 
fossiliferous Cassian marls, sometimes the older dolomite rocks 
(Mendola Dolomite), sometimes volcanic lavas. Von Richt- 
hofen suggested that the variation in the age of the deposits at 
the base of the calcareous or dolomite cliffs, as well as the 
great inequality in the dimensions of the cliffs, might be 
explained in the sense of Darwin's theory on the supposition 
that the cliffs represented coral reefs whose growth had in- 
creased during a prolonged epoch of subsidence of. the sea- 
floor, and had spread over deposits of different ages at the 
base. Mojsisovics, in conjunction with other members of the 
Austrian Survey, afterwards examined the area in greater 
detail, and in 1879 published his work, The Dolomite Reefs of 
South Tyrol, in which he confirmed Richthofen's suggestion 
that the cliffs were fossil coral reefs, but declared the growth of 
the reefs to have been contemporaneous with the sedimentation 
of the earthy and volcanic rocks in the neighbourhood. 

Giimbel, however, proved the frequent occurrence of species 
ofgyroporella, or sea-algas, in the dolomite rocks of South Tyrol, 


and for this and other reasons he regarded them as in the 
main algal accumulations. Lepsius also thought there were 
no sufficient stratigraphical grounds for regarding the dolomite 
rocks of South Tyrol as other than a marine deposit. But the 
coral-reef theory of origin had very numerous adherents, and 
became a popular explanation for isolated limestone occur- 
rences; for example, Oswald Heer wrote of fossil atolls and 
barrier reefs in the Swiss Jura mountains, and Dupont described 
fossil atolls in Belgium preserved in Devonian rocks. 

Recent researches in the Dolomites represent the occur- 
rence of coral reefs only in insignificant thicknesses seldom 
exceeding 150 feet, sometimes intercalated in the marly volcanic 
rocks, and sometimes in the calcareo-dolomitic rocks. 

Several zoologists contested Darwin's theory Wilkes in 
1849, Ross in 1855, the German geologist Semper in 1863, 
upon the evidence of his exploration of the Pelew or Palaos 
Islands. He found there all the varieties of reef-growth in 
immediate proximity to one another, and older coral rocks 
were present upon the dry land. Hence an explanation based 
upon subsidence seemed inapplicable. Semper formed the 
opinion that the tidal conditions, the breakers, and ocean- 
currents were the chief influences which determined the 
particular mode of growth of a coral reef. 

Similarly, Louis Agassiz (1851) and a number of American 
geologists had studied the coral formations of Florida and 
Tortuga, and could find no evidence of subsidence of the sea 
bottom on which the reefs were growing. These reefs have 
now undergone thorough investigation by Professor Alexander 
Agassiz, the son of the famous glacialist and geologist, and the 
conclusion arrived at by him is that the reefs are growing upon 
a submarine plateau formed by the accumulation of mud, 
sand, and organic remains. The prevailing winds and marine 
currents constantly bring new material towards the plateau, and 
as the latter continues to increase the corals are enabled to 
keep within reach of fresh food-supplies. The whole thickness 
of the Florida reefs, including both the coral limestone and the 
submarine shelf of deposit, was determined by borings to 
be about 50 feet. Agassiz is of opinion that the reefs of 
Cuba, Bermuda, and Bahama, and also the Great Barrier Reef 
of North Australia, may be explained in the same way as the 
Florida reefs. 

Rein published in 1870 the result of observations made on 


the Bermuda reefs. He found only evidences of elevation, 
and came to the conclusion that coral reefs could be formed 
wherever the fundamental conditions for the existence of the 
polyps were satisfied, and a firm basis of support was present; 
and it was quite indifferent whether the basis was a submerged 
coast, a submarine plateau of elevation, or a submarine volcano. 
Sir John Murray arrived at similar conclusions (Proc. Roy. Soc. 
Edin.y 1880). He does not accept the hypothesis that the 
atolls and barrier reefs of the Pacific Ocean are built upon 
a submerged continent, but believes the coral polyps settle 
upon isolated volcanoes which still are partly above the water, 
but have been in some parts abraded to the limit of the 
mechanical activity of the waves ; and he correlates the different 
forms of the reefs with conditions of nourishment and processes 
of erosion and corrosion. Murray's explanation of lagoon 
reefs is that on the windward side the existence of the coral 
colonies is more prosperous, and the reef grows more quickly 
than on the leeward side, whose position is less advantageous 
for the constant renewal of food supplies. The polyps on that 
side die, and the reef passes through processes of decay; the 
excavation of the saucer-shaped lagoon is due to the corrosion 
of the reef limestone by sea-water strongly impregnated with 
carbonic acid, and also to the erosive activity of the high tides. 

Another important point in which Murray differs from the 
results attained by Darwin and Dana is the thickness of coral 
reefs. He shows from numerous soundings taken along the 
outer edge of atolls and barriers, that the reef-wall is precipitous 
only to a depth of about 200 feet; below that there is a talus 
slope occupied by broken blocks of coral limestone to depths 
of about 1000 feet; and fragments of volcanic material begin 
to occur at still greater depths. 

In the Salomon Isles Guppy found older coral reefs that 
had been elevated to heights of more than 900 feet, but the 
reefs were not more than 130 feet thick. 

In general, it may be said that most scientific authorities on 
coral reefs at the present day no longer accept Darwin's theory 
of widespread subsidence as applicable to the American and 
Australian reefs, or to those of the Red Sea. On the other 
hand, subsidence seems to be the most satisfactory explanation 
of many atolls in the Pacific Ocean. Clearly the critical test 
for subsidence is the thickness of a reef. The borings under- 
taken at the Ellice Isles, under the guidance of Professor Sollas 


in 1 896, had unfortunately to be given up on account of disasters 
to the instruments. The expedition sent out from Sydney 
University to the Funafuti Atoll under Professor Davis in 1897 
was more successful, and the preliminary reports state that the 
borer passed through 643 feet of reef limestone without reaching 
the fundamental rock. But until the bore samples have been 
examined microscopically no opinion can be formed regarding 
the true nature of the limestone. Professor Agassiz visited the 
Fiji group in 1897, and observed massive coral reefs more than 
600 feet thick in several of the islands. As these reefs had been 
elevated, Agassiz points out that the Pacific Ocean in the 
vicinity of the Fiji Isles cannot be at present undergoing the 
movement of subsidence assumed by Darwin and Dana, but 
rather a movement of elevation, although these massive coral 
reefs must have been formed during some foregoing period of 

Some of the most remarkable products of organic activity 
are the hydrocarbon compounds which, in the form of asphalt, 
naphtha, petroleum, impregnate sedimentary rocks belonging 
to different geological ages. Fluid petroleum is usually 
accompanied by greater or less quantities of inflammable gases, 
while these may be absent in the rocks impregnated with 
asphalt or other solid bitumen. Petroleum and naphtha 
occur exclusively in deposits from salt-water, and very 
commonly in loose sandy strata or in porous dolomitic and 
calcareous rocks where these repose upon, and are succeeded 
by, impervious shales. 

In Pennsylvania, Ohio, and Indiana, certain horizons of 
the Silurian and Devonian formations contain enormous 
quantities of petroleum and inflammable gases ; the naphtha and 
petroleum wells at Baku on the Caspian Sea, and at Grosny on 
the north side of the Caucasus, are apparently inexhaustible ; 
and in Further India the so-called Rangoon oil has been 
found in quantity. The Caspian, Caucasian, Roumanian 
and Galician petroleum occurs in sandy strata of Oligocene 
age ; both here and in Pennsylvania the oil is always in 
greatest abundance at the crests of crust anticlines. 

During the last forty years geologists have rapidly advanced 
our knowledge of the occurrences of these natural oils, but it 
has been less easy to explain the process of their manufacture 
in nature over extensive areas. Berthelot, the chemist, 
suggested (1866) that they were produced when water with 


carbonic acid in solution came in contact with the alkali 
metals. Mendelejeff likewise believes in the action of 
subterranean water upon certain iron ores and metallic carbides 
at high temperatures. But these theories have not been 
accepted by geologists, as they are not in harmony with the 
occurrences of the oil. All other hypotheses consider the 
decay of organic substance essential to the production of 
the series of mineral oils. Bischof in his Chemical Geology 
derives asphalt and petroleum from the slow decay of 
vegetable matter, an explanation which he bases upon the 
frequent occurrence of marsh-gas in peat-mosses. Quenstedt 
thinks the impregnating oil in the Swabian shales has been 
originated by the decomposition of fishes and other animal 
organisms interred in the shales. A similar explanation is 
given by Sterry Hunt for the petroleum oils in North America. 
While Quenstedt and Hunt regard the oil as produced in situ 
in the strata containing the decaying organisms, many 
geologists hold the opinion that the hydro-carbonaceous 
products of decay collect in the stratigraphical horizons above 
those which actually contain the decaying material. 

Engler tried experimentally to distil fish-train oils ; under a 
pressure of 20 to 25 atmospheres, and at a temperature of 
365 to 420, a distillate is procured which approaches the 
characters of the natural Pennsylvania!! petroleum, and, as 
Heusler has shown, after treatment with aluminium chloride, 
is identical with it. 

Ochsenius argues that the mineral oils have been prepared pre- 
eminently in shallow estuaries where animal remains and algse 
have undergone decomposition in salt-water containing a rich 
supply of chlorides, more particularly magnesium chloride. 

It has been observed by Andrussow, Natterer, and Barrois, 
that petroleum in minute quantity bubbles up to the surface of 
the water and mud in the Kara Boghaz on the shores of the 
Caspian Sea, in Bitter Lakes of the Isthmus of Suez, and 
in the desiccating saline basins of Brittany, all of these being 
localities where considerable accumulations of animal remains 
and plant detritus collect. 

E. Volcanoes. The controversy between Neptunists and 
Volcanists, which had still continued keenly in Germany 
during the early years of the nineteenth century, relaxed 
after the desertion of Alexander von Humboldt and Leopold 


von Buch from the ranks of extreme Wernerians. Nowhere 
was the re-action in favour of accurate investigation of vol- 
canoes keener than in Germany, where Werner's remarkable 
influence had so long retarded progress in this important 
branch of teaching. Von Humboldt's works (p. 66) gave 
the first broad conceptions of the arrangement and distribution 
of volcanoes on the earth's surface. From the characteristic 
arrangement of volcanoes either as groups or in long series, 
from their occurrence in all parts of the globe, and from their 
frequent association with earthquakes, Humboldt concluded 
that the cause of volcanic phenomena could not be local, 
but must bear some relation to the constitution of the earth's 
interior. The serial arrangement of volcanoes led him to 
believe that the volcanic vents were disposed upon crust- 
fractures which extended to very great depths. 

Leopold von Buch's visit to Auvergne in 1802 convinced 
this geologist that the volcanic phenomena of that neigh- 
bourhood could only have been produced by some general 
cause associated with the earth's internal heat. It was on 
this occasion also that Leopold von Buch formed his first 
crude conception of the theory which, under the name of 
"Elevation-Crater" theory, was destined to become notorious 
in geological controversy of the nineteenth century. At this 
time, however, Buch merely mentioned a central elevation of 
the Mont d'Or range caused by subterranean forces. 

Von Buch's treatise, On the Geognostic Relations of the Trap 
Porphyry (1813), contains a careful account of the occurrence 
and mineral constitution of rocks belonging to the trachyte 
series. The central elevation, which he had assumed for the 
Mont d'Or and Cantal area, is in this work applied to other 
volcanic regions, for example to the Santorin Island, to the 
trachyte mountains of Hungary, and to the South American 
Cordilleras, and a distinction is drawn between true volcanoes 
and mountain-systems representing dome-like crust elevations 
pushed up by subterranean forces. 

Accompanied by the Norwegian botanist, Christian Smith, 
in the summer and autumn of 1815, Von Buch explored the 
Canary Islands, the Palma Islands, and on the return voyage 
visited the Lancerote Island. The result of this journey was 
published independently by Buch, as Christian Smith died in 
the following year on the Congo river, where he had gone with 
Tuckey's Expedition. Von Buch's descriptive monograph of 


the Canary Islands is full of information for the geographer, 
meteorologist, botanist, and geologist. The chapter on the 
geological relations is a model of skilful and methodical 
exposition. The form, the structure, the composition and 
origin of the different islands, the constitution of the rocks 
and volcanic ejecta, are depicted in a manner at once 
attractive and scientific, and the context is illustrated by 
topographical maps of Teneriffe, Palma, and Lancerote, 
prepared exclusively from surveys and drawings made by 
Von Buch. At the Peak of Teneriffe and in the wonderful 
basin-shaped depressions (" Calderen ") in Palma and Canaria, 
Von Buch found new evidences of volcanic elevations. And 
from this time forward the "Elevation Crater" became one of 
his pet theories. 

The first public enunciation of the theory was given by Von 
Buch on the 28th May, 1819, in the Berlin Academy. He 
defined true volcanoes as solitary, conical mountains almost 
always composed of trap-porphyry (trachyte), and from which 
fire, vapour, and stone are emitted. . They are surrounded by 
molten rock or ashy material which flows downward in the 
form of streams. Typical volcanoes are distinguished by Von 
Buch's theory from larger basaltic masses which after emission 
have been uplifted around the areas of volcanicity. These vol- 
canic uplifts were said to be characterised by the absence of 
lava streams or of accumulations of rapilli round a central 
area, and likewise by the predominance of basaltic over 
trachytic rocks. The basaltic masses are inclined similarly to 
sedimentary strata in any upheaved area ascending from every 
side towards a great central cauldron, or crater of elevation. 
This crater might be afterwards closed by the collapse of the 
upheaved rocks, and might be opened intermittently by fresh 
volcanic ebullitions from below. 

Von Buch then argued that the force required to create 
such a crust-disturbance must be enormous, and must repre- 
sent the prolonged accumulation of a store of energy in the 
earth's interior. The expansive force of the heated lava first 
bulging the rocks upward like a blister or dome, might go on 
increasing until it rent them asunder and provided an outlet 
for the ascending vapours. No true volcano formed unless, 
as frequently happened, a central cone of ejected material 
gathered within the crater of elevation. 

The upper basaltic layers of the crater of elevation might, 



v Von Buch allowed, have flowed into their present position, 
but not superficially like the lava streams of an active volcano, 
only below the surface and under great pressure. The more 
important points in Von Buch's chain of evidence were the 
occurrence of coarse-grained crystalline rocks in the bottom 
of the Palma cauldron, the general arrangement of the strata 
sloping away from the central crater and penetrated by numer- 
ous dykes, and the presence of deep ravines (Barrancos), 
which he regarded as eruptive fissures on the outer side of 
the crater of elevation. Von Buch thought craters of elevation 
were very numerously distributed ; some of them originally 
embracing a central volcanic cone, for example, the island of 
Bourbon ; others, such as those of Auvergne, the Siebenge- 
birge near Bonn, the Lipari Isles, Etna and the American 
Cordilleras, being trachytic dome-shaped mountains situated 
above the fissures of elevation, and either remaining intact at 
their summit or providing themselves with orifices of ejection. 

Von Buch sub-divided all the volcanoes on the earth's sur- 
face into two classes central and serial. The former, accord- 
ing to Von Buch, are located centrally with reference to a 
large number of outbreaks radiating in all directions; the 
latter mark the position of long crust-fissures, and either form 
the highest ridge of a terrestrial mountain-system, or if the 
volcanic fissure be submarine, the highest summits emerge as 
islands above the ocean. 

While Von Buch in his theory tacitly accepted Hutton's 
principle, that the upheaval of the solid rocks was due to the 
expansive force of subterranean heat, he re-cast this doctrine 
into the particular form required to explain his own con- 
ceptions of volcanicity. He formed the erroneous idea that 
the inclination of the basalts around a volcanic vent could 
only be due directly or indirectly to crust-elevation, and this 
view shipwrecked a theory which otherwise embodied some 
valuable generalisations. Adapting his theory to the termin- 
ology of the present day, Von Buch's conception of a "Central 
elevation-crater " represented a local exhibition of crust-expan- 
sion accompanied by a local inrush of molten and gaseous 
material towards a centre of crust-weakness, and the escape of 
the same at a central vent; Von Buch's "Serial elevation- 
craters" represented the results of a regional exhibition of 
the expansive forces due to internal heat, and regional admis- 
sion of molten rock and gaseous vapours into zones and areas 



of weakness. His description of basaltic inflows into sub- 
terranean cavities formed by crust-expansion and elevation 
anticipated later conceptions of laccolitic occurrences of 
volcanic material. 

Before Von Buch had completed his work on the Canary 
Islands for publication, the Englishman, Dr. Daubeny (1819), 
published a tabulated summary of active volcanoes, together 
with an enumeration of all volcanic and earthquake phenomena 
reported within historic times. In 1824 the second volume 
of Carl von Hoff's work appeared, and it embraced an ex- 
haustive account of surface changes associated with volcanic 
outbreaks and earthquake shocks. Von Hoff followed the 
opinions of his compatriots, Humboldt and Buch, on all ques- 
tions regarding the origin and destruction of volcanoes. 

A series of careful researches was carried out in the volcanic 
areas of the Rhine Province by Johann Steininger, a teacher in 
the Treves public school. Steininger established the differ- 
ence between the volcanic rocks of the Eifel district and the 
trap-porphyry rocks (melaphyre, porphyrite, palatinite) of the 
district of Oldenburg and the Palatinate. Both were regarded by 
Steininger as submarine in origin, but he referred the eruptions 
to quite different geological ages. He pointed out that a 
characteristic feature of the Eifel volcanoes was the frequent 
occurrence of lava and volcanic slag and ash without any sign 
of an orifice or eruption. The volcanoes of the Lower Rhine 
district, especially the Siebengebirge, near Bonn, were explained 
as upraised conical mountains in which the volcanic material 
seldom escaped at the surface. In his Contributions to the 
History of the Rhineland Volcanoes, published in 1821, 
Steininger proved that a certain number of the volcanoes, 
chiefly those on the right bank of the Rhine, had originated 
contemporaneously with the formation of the brown-coal 
deposits (Tertiary), and were therefore older than the pebble 
and clay deposits with fossil mammalian bones (mammoth, 
rhinoceros); but, he added, the products of the youngest 
volcanoes on the left bank of the Rhine seemed to be dis- 
tributed above these pebble-beds, and might accordingly 
belong to historic times. The idea of the quite recent occur- 
rence of those volcanoes originated from a mistaken reading 
of a reference made to the volcanoes of this area by Tacitus. 

In his earlier writings Steininger was under the influ- 
ence of Von Buch's theory of elevation-craters, but his close 


acquaintance with the mode of occurrence of the volcanic 
rocks in Rhineland enabled him gradually to form his own 
judgments, and these were unfavourable to Von Buch's 
theory. A visit to Auvergne, Mont d'Or, and the Cantal moun- 
tains still further shook his confidence in it. He examined 
the basaltic rocks above the Tertiary fresh-water limestone 
of Limagne, and felt convinced that these could not have 
been bulged up as solid rock from the ocean-floor, but must 
have flowed into their present position superficially as a lava. 
Again, he could see no evidence in favour of Von Buch's 
hypothesis that the ravines of the Cantal represent eruptive 
fissures formed during upheaval, but rather believed them 
to be ordinary erosion valleys. Steininger, however, con- 
tinued to retain Von Buch's theory of volcanic upheaval as 
applicable to the particular cases of isolated conical hills 
composed of domite or trachyte rock. 

The strongest opponents of Von Buch's theory were, however, 
Poulett-Scrope, 1 Charles Lyell, and Constant Pre'vost. 

In 1816-17, Poulett-Scrope, as a young student, had the 
opportunity of observing the volcanic surroundings of Naples, 
and this gave the impulse to his scientific studies. He 
returned in 1818, 1819, and 1822 to Southern Italy, and 
visited Vesuvius, Etna, the Lipari Isles, the neighbourhood 
of Rome, and the Euganian Isles. In 1821 he spent several 
months in the Auvergne district,' and in 1823 he made him- 
self acquainted with the Rhineland and Eifel volcanoes 
described by Steininger. 

In 1825 he published his famous work on Volcanoes, and 
in 1826 his excellent monograph of the extinct volcanoes in 
Central France. Poulett-Scrope's works have held their 
position as the basis of volcanic teaching. Like Hutton and 
his own contemporary, Charles Lyell, he was a Uniformitarian, 
and tried to explain the events of past geological ages by the 
action of forces which exist. 

Observing the enormous expansive force of the aqueous 

1 George Poulett-Scrope was born in 1797 in London, the son of a rich 
merchant, J. Poulett Thomson ; he studied in Cambridge under Professor 
Sedgwick, and assumed the name of Scrope after his marriage with the 
heiress of the old Scrope family. Pie became a Member of Parliament in 
1833, anc l afterwards devoted himself mainly to political activity, but did 
not neglect his studies on volcanoes. In 1867 the Geological Society 
conferred the Wollaston medal on him. He died at Fairlawn, Surrey, in 
January 1875. 


vapour and gases which escaped from a lava stream at the 
surface, Scrope formed the opinion that eruptive phenomena 
might be traced to the mobility of the lava. According to his 
observations, lava, as it issues from a volcanic vent, very 
seldom has the appearance with which we are familiar in a hot 
mass of iron or glass, but is usually in a viscid, seething 
condition, impregnated with elastic vapours, and enclosing 
many crystallites which move freely in the surrounding fluid 
in virtue of the passage of the vapours through it. As the 
vapours explode and escape, the motion of the mineral 
constituents is impeded and the lava solidifies. Scrope 
applied this theory to subterranean lava. He supposes a fused 
rock-mass saturated with water, under pressure of super- 
incumbent solid rock ; then the pressure being the same and 
the temperature raised, or the temperature being the same and 
the pressure relaxed, the water will pass into the condition of 
vapour, and a certain amount of heat be made latent. The 
crystalline constituents of this subterranean magma are 
separated by the elastic vapour, the lava swells and passes into 
a fluid condition. The degree of liquidity in the whole mass 
was thought by Mr. Scrope to depend chiefly on the weight of 
the mineral constituents and the fineness of the crystals. If 
the subterranean lava be horizontally extended, the compressed 
vapours, in trying to escape, press the lava against the upper 
strata, cause earthquakes, and finally fissures into which the 
seething lava flows. If the fissures widen towards the interior 
of the earth, the rising lava forms dykes, and as these narrow 
towards the earth's surface, they strengthen the crust ; but if, 
on the other hand, the fissures are wider in the upper horizons 
of the crust than in the lower, they remain -partially open, and 
form relatively weak parts in the earth's crust, readily liable to 
renewed eruptions. 

Scrope endeavoured to explain all the phenomena associated 
with volcanic eruptions upon the basis of the above theory. 
In favour of it, he noted the periodicity in eruptive activity ; 
how after each eruption, when presumably the fissures have 
been blocked with rock-material, a period of rest ensues, but 
when the vapours have once more accumulated in the deep 
volcanic magma, the old vent again bursts open or a new 
orifice forms. In the case of land volcanoes, the ejected 
products of successive outbursts surround these orifices with 
the characteristic circular or elliptical form. The particular 


form of the volcano is determined by several causes, for 
example, the inequality of the ground, violent winds during 
eruption, or any obstacles within the vent which may impede 
the ascent of the lava, or direct it into another course. 
Stratification is apparent in the structure of the cone of 
ejection ; it is especially clear when there is an alternation of 
lava and volcanic ash. The inclination of the layers of 
volcanic rock is always from the edge of the crater to the base 
of the cone. The liquidity of the lava depends on its 
composition, texture, and temperature, and according to these 
and to the superficial relations, the solidified lava assumes the 
form of horizontal sheets, thick masses, or dome-shaped cones. 
During the cooling of the lava the escape of the vapours gives 
origin to the slaggy, vesicular structure of the lava; the 
liberation of the gases from the lava produces all kinds of 
minerals, and may take place either in association with 
escaping vapours as " fumaroles," or independently as gaseous 
emanations or " solfataras " ; sometimes the gases collect from 
hot springs, or they vanish as exhalations. Pillar-shaped, 
rounded, cubical, rhomboidal, flaggy or shaly structure 
develops in consequence of the contraction of the lava 
during the processes of cooling. 

As one and the same volcano may emit basaltic and trachytic 
lavas, Scrope thought it probable that all volcanic products 
come from the same subterranean magma, and that their 
specific difference is due to some condition connected with 
the access of heat and the subsequent chemical processes 
during their ascent. Poulett-Scrope opposed the conception 
of Humboldt and Buch, that trachyte and basalt rocks are of 
different ages. The larger volcanic mountains, he said, clearly 
owe their origin and form to repeated eruptions ; the original 
cones of ejection are rent by later outbreaks, and the repeated 
outpourings and injections of lava still help to strengthen 
the mountain. In the summit crater, for the most part only 
vapours escape, together with the blocks and fragments which 
are carried up by the explosions. Very wide and deep craters 
form during the violent paroxysms of a volcano ; by means of 
the subsequent eruptions new cones of ejection may arise 
within this deep crater, and be surrounded by the circular 
wall of the old crater ; or the wall of the old crater may be 
disturbed and partially destroyed by a new crater (Somma). 

Scrope strongly contested the existence of craters of elevation, 


and he ascribed the domal form of the trachyte mountains not 
to the swelling up of homogeneous masses, but to successive 
outbreaks of viscid lava streams. Neither did he draw any 
fundamental distinction between volcanic eruptions on land 
and those on the ocean-floor. Cones of erupted material form 
in the case of submarine as well as continental volcanoes, 
but owing to the distribution of the material by water, the 
layers of volcanic rock are less highly inclined and generally 
of tufaceous character. Some submarine volcanoes have their 
cones of ejection built up by repeated additions until they 
rise above the surface ; others (e.g., lie de France, Teneriffe, 
Palma, the Coral Islands in the Pacific Ocean) may, in Scrope's 
opinion, have been arched to their present position by the 
subterranean forces of heat. The difference between the 
"craters of elevation " of Von Buch and the uplifted islands 
of Scrope is that the former are supposed to have received 
their characteristic form and their crater, independently of any 
accompanying phenomena of eruption, merely by the upward 
swelling and fracture of the crust, whereas Scrope thinks the 
elevated submarine islands of volcanic rock are in all cases 
originally cones of erupted rock-material accumulated super- 
ficially round an orifice, and afterwards upraised as a whole. 

Von Buch's " Serial Volcanoes " are explained similarly by 
Scrope as volcanic cones which participated in a crust-uplift. 
All volcanoes, according to him, occur upon crust-fissures; 
some eruptive vents are permanently closed, and others 
continue to remain in communication with the earth's 
interior, and are the scene of periodic eruptions. These 
open vents, by affording a ready passage for subterranean 
lava, vapours, and gases, serve to protect the neighbourhood 
from earthquakes. Scrope attached little tectonic import- 
ance to the elevations at volcanic fissures, regarding them as 
quite local in effect, and having no immediate connection with 
the regional crust-movements which elevate continents and 

The above are the leading doctrines of volcanicity taught 
by Scrope, and they may be said to have laid the first secure 
foundation of present conceptions of eruptive phenomena. 
The chief merit of Scrope's work consists in the convincing 
demonstration it gives of the origin and composition of vol- 
canoes, in the disproof of the Elevation-Crater theory, and in 
the description of a superheated subterranean magma saturated 


with water-substance, and brought to the surface in virtue of 
the expansive force of escaping vapours and gases. 

Sir Charles Lyell held views very similar to those of 
Poulett-Scrope. His observations in the Auvergne, and at 
Vesuvius and Etna, had convinced him of the mistaken 
principles in the Elevation-Crater theory. He made the 
pertinent objection that one of the "craters of elevation" 
mentioned by Von Buch was entirely composed of marine 
or littoral sediments ; and he explained the enormous 
"cauldrons" of Palma, Gran Canaria, Bourbon, etc., as 
craters due to volcanic explosion ; and the circular walls of the 
Somma, the Peak of Teneriffe, Etna, etc., as the remainder 
of old crater walls. In common with Poulett-Scrope, Lyell 
ascribed the conical form of most volcanoes to the accumu- 
lation of volcanic products round a vent, and he accepted 
Scrope's view that volcanic eruptions were originated by the 
explosive disengagement of the compressed vapours and gases 
from subterranean magma. His wider geological experience, 
however, led him to the further conclusion that the water- 
substance dissolved in the magma had been introduced into 
it by percolation downward from the surface, and that the 
characteristic occurrence of serial volcanoes on the sea-board 
betokened direct influence of the sea-water upon the sub- 
terranean magma. 

Dr. Charles Daubeny's Description of Active and Extinct 
Volcanoes, etc. (1826), although less full of original matter 
than the works of Scrope and Lyell on kindred subjects, 
was distinguished by greater chemical and mineralogical 
knowledge. His treatment of European volcanoes is based 
for the most part on his own field investigations of the various 
localities, and careful laboratory research of the volcanic rocks. 
Daubeny was favourably inclined to Buch's "Elevation-Crater" 
theory, and thought that Scrope attached too great importance 
to the expansion of vapours, and too little importance to 
chemical processes in his explanation of volcanic eruption. 

Valuable results of .a special study of the Lipari Islands 
were made known in 1832-33 by Friedrich Hoffmann, but the 
complete researches of this gifted writer were first published by 
Von Dechen after Hoffmann's death, in Karsten's Archiv fur 
Mineralogie, 1839. Hoffmann contended that there was no 
essential difference in point of structure between the craters 
attributed by Von Buch to crust-elevation and fissure, and the 


craters regarded by him simply as eruptive orifices. The 
alleged differences resolved themselves into a question of 
comparative dimensions, and these could be explained by the 
varying intensity of the explosive convulsions. 

The French Government had sent Constant Prevost, in 
August 1831, to Pantellaria, in order to study the newly- 
formed Graham's Island, or lie Julia, as the French 
Expedition called it. The island vanished in three months, 
and Prevost was one of the few favoured individuals who 
had succeeded in visiting and making drawings of it. 
After fulfilling this commission, he travelled through Sicily, 
climbed Etna, made a stay in the Lipari Islands, and 
finally met Hoffmann and Escher von der Linth in Naples. 
Excursions made in the company of these geologists to 
Vesuvius and the Phlegrrean fields brought Prevost's 
memorable tour to a conclusion. Several accounts of his 
journeys were sent by Prevost to the Academy of Sciences and 
the Geological Society of ^Paris. 

Meantime, in Paris, Elie de Beaumont (1829-30) had 
discussed the Elevation-Crater theory in various publications, 
and had given it strong support ; and when Prevost in his 
first report on the Island of Julia to the Academy ventured to 
doubt the theory, and in September 1832, in a second report, 
went so far as to openly deny the existence of elevation- 
craters in any volcanic district visited by him, he aroused the 
displeasure of all the leading members of the Academy. Only 
the venerable Cordier, who had seen the Canary Isles, 
expressed agreement with him. In the December of that year 
Prevost won a valuable ally in Virlet, who proved that the 
Santorin group, which had hitherto been included amongst 
elevation-craters, consisted wholly of ejected material. 

In the following years controversy became as keen in the 
discussion of Buch's theory as it had been in Werner's time 
over the discussion of the volcanic or aqueous origin of basalt. 
Annoyed by the attacks on his favourite theory, Buch 
undertook, in the autumn of 1834, another journey to Italy 
along with Link, Elie de Beaumont, and Dufrenoy. New 
evidences were collected, and his views were afterwards 
pronounced even more firmly. " Craters of Elevation are," he 
wrote, "remnants of a powerful manifestation of energy from 
the earth's interior, which is capable of uplifting large islands 
many square miles in breadth to a considerable elevation. 


No phenomena of eruption proceed from them ; no volcanic 
event connects them with the earth's interior; and only 
seldom is there any evidence of continued volcanic activity 
within such craters, or in their neighbourhood." 

The chief argument insisted upon by Buch was the high 
inclination of the lava flows, which he thought proved that they 
had been uplifted after their emission. He never accepted 
Scrope's explanation that the streams of red-hot magma could 
solidify in this position. Elie de Beaumont examined Etna, 
and, after accurate measurements of the angle of inclination, 
likewise refuted the possibility of solidification in situ. He 
allowed rather more significance than Von Buch to the 
accumulation of ejected scoriae and debris, but held upheaval 
for the most important factor in the formation of a volcanic 
cone. Wilhelm Abich and Sainte-Claire Deville were amongst 
the more able supporters of the Elevation -Crater theory ; 
Abich in his illustrative work on Vesuvius and Etna (1836), and 
Deville in his description of the Eruption of Vesuvius in 1855. 

Von Buch's theory was now thought to have been 
successfully defended, and was accepted in the standard text- 
books, in the monographs of Daubeny and Landgrebe, and 
above all in the Cosmos of Humboldt. But the three chief 
antagonists of the theory, Constant Prevost, Lyell, and Poulett- 
Scrope, continued to publish their own views, and in two 
masterly polemical papers in the Quarterly Journal of the 
Geological Society of London (1856 and 1859), Scrope was able 
to endorse the opinions he had formed thirty years earlier, 
and to demonstrate the origin of volcanic cones from ejected 
material in a manner absolutely convincing. 

During the following decade, corroborative evidence in 
the same direction rapidly gathered in geological literature. 
Dr. George Hartung, who had been with Sir Charles Lyell in 
the Canary Islands, and had also made a number of 
observations in Madeira and the Azores Islands, openly 
disputed Von Buch's views in Germany, and said that the 
present shape of the large "cauldrons" in Palma and Gran 
Canaria had been produced by erosion. Dana's investigations 
in the Sandwich Isles and Junghuhn's excellent descriptions 
of the volcanoes in Java added further records of volcanic 
cones built up by ejected material; and Fouque in 1866 
arrived at the conclusion that in the case of the Santorin 
Islands Buch's theory could not be applied. Thus the 


hypothesis of Elevation-Craters had to be given up, and with it 
the classification of volcanoes into "True" or "Eruptive 
Volcanoes" and "Craters of Elevation" which had been so 
long associated with the names of Buch and Humboldt. 

Karl von Seebach then proposed a new classification ; he 
distinguished as Stratified Volcanoes those which have a crater 
and are composed of layers of lava and loose volcanic ash and 
scoriae ; as Homogeneous Volcanoes those which have no crater 
and no loose ejected material but have originated as massive 
effusions and have the form either of volcanic domes or 
horizontal sheets. The homogeneous volcanoes have been 
formed by viscous lavas, the stratified volcanoes by more 
liquid lavas strongly impregnated with vapour and gases. 
This sub-division into stratified and homogeneous volcanoes 
was adopted in most of the text-books, and was afterwards 
more firmly established by Sir Archibald Geikie and Dr. Reyer. 

It is beyond the scope of this volume to enter into the 
extensive descriptive literature which is occupied chiefly with 
the configuration, composition, geographical distribution, erup- 
tive phenomena, and history of the volcanoes. Humboldt 
published an epitome of all known volcanoes, and the works 
of Hoff, Daubeny, Scrope, and others supplemented the 
earlier lists. 

Vesuvius is the best known volcano in the world, and 
during the prolonged controversy about elevation-craters 
was made more than ever the subject of close attention. 
Monticelli for thirty years, from 1815 to 1845, took observa- 
tions on Vesuvius and its discharges; from 1855 to 1892 
Palmieri published regular reports of the observations made 
in the Observatory of this mountain. Angelo Scacchi and 
Gerhard vom Rath examined the minerals of Vesuvius ; the 
lavas were described by Justus Roth, the author of a 
monograph of Mount Vesuvius (1857), and by C. W. C. Fuchs. 
The last-named author also mapped and described the Island 
of Ischia (1872). Within recent years Vesuvius has been con- 
stantly under observation by Johnston Lavis and Matteucci. 

The name of Baron Sartorius von Waltershausen is indelibly 
associated with Etna. His geological map (scale, i : 50,000) 
of this volcano appeared in 1861, and his descriptive text was 
published posthumously in 1880 by Lasaulx. The scrupulous 
accuracy and exhaustive details of both map and text amply 
entitle them to their rank as the fundamental work on Etna. 


Von Waltershausen brings forward evidence to show that the 
first volcanic outbreak on Etna took place during the Diluvial 
period, while that area formed part of the Continent ; whereas 
Pilla, writing in 1845, referred the first Etna eruption to the 
Pliocene age, or possibly to a still more remote period. 
According to Von Waltershausen, the volcanic eruptions are 
concentrated along a fissure extending in N.N.W.-S.S.E. 
direction ; and the famous Val del Bove is thought by him to 
have originated as a crust-inthrow, and is compared with the 
crust-basins of Somma and Santorin. 

The Lipari Islands have called forth a rich literature. 
Special interest has been accorded to a ringed series of 
islands and reef-rocks surrounding Stromboli on the south. 
Hoffmann in 1832 suggested that these probably represented 
the fragments of a former enormous crater. Professor Judd 
in 1875 confirmed this view, and also agreed with Hoffmann's 
conclusion that the vents of the volcanic discharges in the 
Lipari Isles virtually occur along the course of three radial 
fissures. Professor Suess expressed a similar opinion that the 
^Eolian Isles mark a saucer-shaped depression in which radial 
faults intersect. 

The Santorin Isles form the subject of a splendidly 
illustrated monograph by Fouque. Since its publication in 
1878, a number of geologists have contributed special papers 
on the surface conformation, the geological structure, the 
origin and history of these volcanic islands. All newer 
publications agree that the theory of the Elevation-Craters is 
quite inapplicable to Santorin. 

The volcanoes of Iceland have been carefully investigated 
during the past century. Mackenzie's Travels gave the 
earliest detailed reports (1811); in 1846, the great chemist 
Robert von Bunsen travelled through Iceland, and published 
five years later his famous treatise on the chemical composition 
and origin of the volcanic rocks of Iceland. Within recent 
years the island has been accurately mapped by members of 
the Norwegian Survey Department, and important contribu- 
tions have been made to the knowledge of its volcanoes by 
Thoroddsen and Keilhack. 

The extinct volcanoes of Europe have received a large share 
of attention from geologists. The Euganian Isles near Padua, 
and Monte Berici near Vicenza, have been studied by Dr. vom 
Rath, Dr. Reyer, and Professor Suess. 


The extinct volcanoes of Central France, the Eifel and the 
Siebengebirge, have been frequently mentioned in the fore- 
going pages. Other favourite themes in geological literature 
are the basalt and trachyte domes of the Westerwald, the 
extensive volcanic district of the Vogelsgebirge, the extinct 
volcanoes in the vicinity of Cassel, in the Habichts Forest, 
Kaufung Forest, and the Meissner Mountain. As early as 
1790, a mineralogical study of the Meissner was published by 
J. Schaub, and a geological map of this mountain appeared 
in 1817. 

The Rhon has a historical interest for geology, as it was the 
basis of Voigt's attack on the Neptunistic doctrines of his 
teacher Werner. The mode of occurrence of the phonolite 
and basalt bosses in the Rhon convinced Voigt of their 
volcanic origin. The first complete description of the Rhon 
was given in 1866 by C. W. von Giimbel, in whose works on 
Bavarian geology will be found all the important features of 
the ancient centres of volcanicity in the Bavarian Forest. 
Another district exhaustively treated by Giimbel is the 
volcanic inthrow of the Ries. The basalt hills and tuff dykes 
of the Swabian Alp have been examined by Quenstedt (1869), 
Zirkel (1870), and more recently by W. Branco (1894). 
Professor Branco contests the hypothesis that all volcanoes 
occur upon tectonic fissures and faults. 

In the Hohgau in Baden phonolite and basalt mountains 
rise to a height of nearly 3000 feet. They present for the 
most part the characteristics of homogeneous volcanic rock, 
but are partly accompanied also by masses of tuffs. The 
pretty little volcanic mountain known as the Kaiserstuhl rises 
from the Rhine Plain between the Black Forest and the Vosges 
mountains. Baron von Dietrich in 1774 was the first to 
recognise its volcanic origin. 

The basaltic bosses in Thuringia, Saxony, and Silesia, as well 
as the extinct volcanoes in North Bohemia, Hungary, and 
Transylvania, have been the subject of petrographical papers, 
but have had no marked influence upon general conceptions of 
volcanism. The Kammerbiihl near Eger has some historical 
interest, and a new paper was published upon it by Prost 
{Jahrbuch) 1894). 

The writings on the district of Predazzo and the neighbour 
ing parts of the Fassa Valley and Schlern fill an important 
page in the history of volcanism. In 1819 Count Marzari 


Pencati had drawn attention to the fact that not far from 
Predazzo, at the waterfall of Canzacoli, true granite covered 

he Alpine limestone and had altered it to marble. Leopold 

7on Buch doubted in 1821 the position of the granite above 

he limestone, but allowed that the granite had produced the 
metamorphism of the limestone to marble. Then followed 

3uch's famous papers on dolomite, and on the geology of the 
Fassa Valley, in which he on the one hand tried to explain the 
origin of the dolomite by the action of magnesia vapours 
during the eruption of augite porphyry, and on the other hand 
associated the upheaval of the Alps with the outbreaks of 
augite porphyry. 

Buch's declaration that in South Tyrol lay the key to 

he solution of Alpine geology, attracted geologists from all 
countries to this neighbourhood. The " Triassic granite" and 
Monzoni syenite, with their wonderful array of contact 
minerals, the dykes and massive sheets of augite porphyry, 
melaphyre and liebenerite porphyry, were described by several 
geologists. In 1824 Poulett-Scrope, Studer, and Ami Boue' 
visited Predazzo ; in 1843 Von Klipstein published his obser- 
vations on the Fleims and Fassa Valley; in 1855 the Nor- 
wegian mineralogist, Kjerulf, published his accurate mineral- 
ogical and chemical investigation of the Monzoni syenite. 
Baron von Richthofen's monograph, published in 1860, still 

brms the best foundation for the geology of South Tyrol. 

rle determined a definite succession in the Triassic eruptive 
rocks first the basic series, augite, porphyrite, monzonite, and 
hypersthenite, then flows of lava, or the infilling of fissures by 
tourmaline granite, melaphyre, and liebenerite porphyry. 
Three years later Bernhardt von Cotta's paper appeared on 
the intrusions and ramifications of the Monzoni syenite into 
the limestone, on contact minerals, and on the melaphyre 
dykes in the limestone and dolomite. Lapparent in 1864 
sub-divided the eruptive rocks of the neighbourhood into a 
basic and an acid group, without entering into the particular 
succession, but Doelter's petrographical studies led him to 
much the same conclusion about the succession as Richthofen 
had formed. Reyer, on the other hand, thought that granite 
and then syenite had been intruded during the Muschelkalk 
period; monzonite, porphyrite, and andesite had followed; 
but in his opinion the same eruptive series had been re- 
peated in various geological epochs. Mojsisovics' work, The 


Dolomite Reefs of South Tyrol, supplies a comprehensive 
account of this district, and forms the text to the Austrian 
Geological Survey Maps. 

More recently the Norwegian geologist, Professor Broegger, 
has drawn a comparison between the rocks of the South Tyrol 
eruptive area and those of the Christiania area. He demon- 
strates that Richthofen's " Melaphyre" of the Mulatto mountain 
is not younger but older than the tourmaline granite, and that 
altogether the basic eruptions of augite, porphyrite, plagioclase 
porphyrite, and melaphyres in the Fassa Valley for the most 
part preceded the intrusion of the granite. Only a few ultra- 
basic dykes which penetrate the granite at Predazzo are younger 
than it. Broegger arrives at the conclusion that granite, 
monzonite, hypersthenite are only the deep-seated equivalents 
of the Triassic outflows of porphyrites and melaphyres; and 
his comparison of the Predazzo and Christiania areas leads him 
to assign a Triassic age to the granite masses at Brixen, and to 
the tonalite, adamellite, and banatite of the Riesenferner group, 
the Adamello group, and Cima d'Asta. 

The extinct volcanoes of the Western Isles of Scotland 
were first described by MacCulloch (ante, p. 113). Ami Boue, 
in his Geological Essay on Scotland (1820), distinguished very 
exactly between basaltic sheets and dykes, and described the 
various volcanic rocks petrographically. Although a student 
of Jameson, he attached himself to Hutton's party in regard to 
the origin of basalt, phonolite, trachyte, porphyry, and granite. 

L. A. Necker, the grandson of the great Saussure, travelled 
in Scotland and the Western Hebrides in 1823, but his account 
of his journey contained little that was new. The observations 
of Von Oeynhausen and Von Dechen, published in Karsten's 
Archiv in 1826, were of some importance for the geology of 
Skye, Eigg, and Arran. 

In 1850, the Duke of Argyle discovered in the Island of 
Mull sedimentary beds with flint nodules belonging to the 
Cretaceous series, and fossil remains of dicotyledonous plants 
between basaltic flows. The fossils were determined by 
Edward Forbes to be of Tertiary age; nevertheless the same 
author referred the basalts of Skye to the Jurassic epoch. 
In 1 86 1, Sir Archibald Geikie began that brilliant series of 
researches which extended over a period of thirty-five years, 
and made the Western Isles of Scotland a classical area for 
the study of extinct volcanoes. 


Geikie at first agreed with Edward Forbes as to the geolo- 
gical age of the basaltic flows in Skye, but further researches 
led him to form another conclusion, and in 1867 he wrote that 
all the eruptions of basalt in the Western and the Faroe Isles, 
as well as those in Iceland, had taken place during the Tertiary 
epoch, and that the individual outbreaks had been separated 
by long intervals of time, during which fresh-water deposits, 
conglomerates, and even thin coal-seams had accumulated. 
The volcanic flows covered considerable areas and solidified 
quickly into compact basalt, sometimes to spheroidal or 
columnar basalt. Forbes had already expressed the opinion 
that in Scotland it was not a question of submarine but of sub- 
aerial eruptions, and Sir Archibald Geikie confirmed this view. 

While Geikie was still engaged in his field investigations, 
Professor Judd published a paper on the extinct volcanoes of 
the Scottish Highlands, in which he tried to prove that the 
volcanic outbursts had proceeded from five great central 
volcanoes. Judd supposes three periods of eruption, the first 
characterised only by acid rocks (felspathic lavas and granite), 
the second by basalt and basaltic tuff, and the third by the 
formation of sporadic volcanic cones of various constitution. 
Geikie contested these views in a series of papers whose con- 
tents are comprised in the second volume of his work, The 
Ancient Volcanoes of Great Britain, published in 1897. 

No basaltic region in the world has been examined and 
described with the same accuracy as the Western Isles of 
Scotland. Sir Archibald Geikie has convincingly proved the 
order of succession of the different contemporaneous flows, 
the age of the various intrusive sheets and dykes, the occur- 
rences of fossiliferous strata interbedded between the contem- 
poraneous basaltic flows, and has also demonstrated the 
presence of ancient necks and in several places even vestiges 
of original craters on the surface of the older lavas. Through 
his exposition of one of the most involved and puzzling pieces 
of research undertaken in any country, Geikie has thrown new 
light upon the history of extinct volcanic action. In his hands 
this typical district of ancient volcanicity has revealed to the 
geologist many fundamental principles of correlation in the 
subterranean and surface distribution, and in the consolida- 
tion of rock-magmas, which are of the highest significance for 
the study of homogeneous volcanic rock. The diverse and 
often marvellously beautiful scenic effects produced in the 


volcanic rocks by subsequent denudation have been treated 
with no less careful observation and insight. 

In the course of his researches, Geikie did not confine 
himself to the Scottish volcanoes of Tertiary age. The first 
volume of his important work treats the older volcanic rocks 
of Great Britain from the Pre-Cambrian to the close of the 
Permian period. Geikie does not admit any essential differ- 
ence between old and modern volcanoes, and he judges all 
massive outpourings, sills and dykes, homogeneous bosses and 
cones, from this standpoint. On the one hand, the phenomena 
of past periods are read in the light of recent manifestations 
of volcanic action; and vice versa, the stratigraphical relations 
of the submarine tuffs and massive outbreaks of the Palaeozoic 
era are used to elucidate certain of the recent phenomena 
which are removed from present observation. In this volume, 
examples are described of typical stratified volcanoes in the 
Silurian and Devonian formations of Wales and Scotland, the 
extensive fissure-eruptions of the Carboniferous epoch in 
Scotland, and the scattered homogeneous domes or tuff-cones 
which took origin in England during the same epoch. In the 
Mesozoic period, Great Britain was marked by almost com- 
plete cessation of volcanic activity. 

The volcanic phenomena of the Faroe Islands have been 
investigated by Professor James Geikie (1880), Amund Helland 
(1881), Breon (1884), and Lomas (1895). These islands 
display a close relationship with the northern areas of Great 

Important contributions to our knowledge of volcanicity 
have been made by Dr. Hermann Abich, in his works on the 
geology of the Caucasian areas. The Persian volcano 
Demavend has also been made the subject of geological 
researches, the Austrian geologist, Dr Tietze, having given 
the most recent account in 1878. Reports of the extinct 
volcanoes of Asia Minor appear in several books of travel 
published about the middle of the nineteenth century; the 
volcanoes in the vicinity of the Dead Sea have been examined 
in some detail by Blanckenhorn and Diener. 

In Asia proper, volcanic activity is at present concentrated 
along the eastern coast-line, on the borders of the Pacific 
Ocean. The volcanoes in Kamtschatka, in the Aleutian and 
Kurile Isles, in Japan, Formosa, and the Philippines, have 
been repeatedly described in geographical and geological litera- 


ture. More special geological papers on the volcanoes of 
Japan have been published by Naumann in Germany, by 
Milne in England, and by Wada and other Japanese authors 
in the scientific literature of Japan. 

Junghuhn's well-illustrated account of the Javanese volcanoes 
holds a distinguished place in the literature, and the pioneer 
work of investigation begun by German explorers was ably 
continued by the later communications of Emil Stohr on the 
Idjen-Raun and the Tenggor volcanoes in East Java, and by 
R. D. M. Verbeek, on the volcanic outbursts which culminated 
in the fearful catastrophe of the Krakatoa eruption in 1884. 

India, although unvisited by recent volcanic action, was the 
scene of colossal outpourings of volcanic matter during the 
Cretaceous epoch. The Geological Survey of India has already 
made known the leading characteristics of the Deccan basalts 
and tuffs which extend throughout a vast territory in the 
heart of India. 

A classical district for volcanic research is the island of 
Hawaii with the two giant-cones Mauna-Loa and Mauna Kea. 
These were described in 1840 by Professor Dana, and in 
1884 a detailed monograph on the Hawaiian volcanoes was 
published by Clarence Edward Button. Charles Darwin's 
"Geological Observations on the Volcanic Islands visited 
during the voyage of H.M.S. Beagle" (1844) laid the founda- 
tion for a new field of volcanic research; and the geological 
results of the Challenger Expedition have contributed materially 
to the scientific knowledge of submarine eruptions. 

The African continental volcanoes, notably the Kamerun in 
the west, the Kilimandjaro and Kenia in the east, and the 
Ruwenzori in the interior, are remarkable for their great size. 
They have been frequently ascended during the last decade, 
and the rocks have been partially investigated, but so far their 
investigation has not contributed much that is new in volcanic 
research. The extensive outpourings of volcanic material in 
Eastern Equatorial Africa are stated to have begun after the 
close of the Jurassic period. 

North America possesses active volcanoes only in the 
extreme north-west, in Alaska and Washington territory. 
These have been described by the geologists of the United 
States; detailed information having already been given of all 
the important areas, Mount Elias in Alaska, Mount Rainier 
(Tacoma) and Mount Hood in the Cascade mountains, and 



the Mono Valley in East California. The magnificent basalt 
plateau in Oregon and Washington, through which the Columbia 
River has channeled its course, was made known to the 
scientific world by Hayden, and the same geologist described 
for the first time in 1871 the wonderful lava plateau in North- 
Western Wyoming, on the banks of the Yellowstone River, 
with geysers, hot springs, mud volcanoes, and extinct volcanic 
hills. Since the Yellowstone Park became in 1872 the 
national property of the United States, the Geological Survey 
Department has carried on without intermission the work of 
scientific exploration and detailed research in this region. 
Professor Iddings has described the volcanic rocks of the 
National Park in two memorable reports of the United States 
Survey (1888 and 1889). 

Farther south, the high table-lands of Colorado, Arizona, 
and New Mexico display a number of extinct volcanoes 
which have broken through horizontal strata of Palaeozoic age 
and repose upon them as widespread sheets or conical hills. 
The volcanoes in Southern Colorado and in Arizona were 
described by Powell, Wheeler, King, Gilbert, and others, and 
in 1882 the United States Survey published Button's admir- 
able monograph of the Grand Canon district. 

The Henry mountains, in the greatly denuded region west 
of the Colorado River, will always be memorable in geology 
as the locality of Gilbert's epoch-making researches on volcanic 
rocks. Gilbert demonstrated there the true nature of certain 
deep-seated intrusions which had made their way mainly along 
the bedding-planes of sedimentary strata, had solidified there 
in cistern-like form, and displaced the surrounding beds by 
their pressure. Such intrusions were termed " laccolites " by 
Gilbert, and in so far as they exert uplifting forces on the strata 
above them, Gilbert's laccolitic intrusions are reminiscent of 
Von Buch's Elevation-Craters. The term of " laccolite," 
together with Gilbert's explanation, is almost universally 
accepted by geologists. Peale, Holmes, and Endlich (1877) 
have shown how, in virtue of denudation and removal of the 
stratified rock-materia 1 , individual laccolites have been exposed 
superficially as dome shaped bosses of igneous rock. 

Alexander von Humboldt was the first to explore the 
Mexican volcanoes, and the German geologists Felix and Lenk 
published, during the years 1888-91, valuable contributions 
to the geology and palaeontology of Mexico. The volcanoes 


of Guatemala and San Salvador were described in 1868 by 
M. Dollfuss-Montserrat, and Dr. Sapper has recently been 
engaged on a series of researches in this area. 

There have been comparatively few geological publications 
dealing with the volcanoes and volcanic rocks of South 
America since the pioneer works of Humboldt. Dr. Alphons 
Stiibel has, however, made a special study of the volcanic 
mountains of Ecuador, and published in Berlin in 1897 a 
special monograph of the district, accompanied by a Geo- 
logical Map. Dr. Stiibel gives a summary of his results in 
the introductory chapter, where he represents his views on 
volcanic phenomena from a general standpoint. He thinks 
it probable that in the first stage of the Earth's cooling, out- 
pourings of magma occurred so frequently, and were of such 
colossal dimensions that the older volcanic material had only 
partially solidified when younger outflows burst forth and 
spread above them. In this way the cooling of the older 
magmas was indefinitely delayed, and they continued as local 
"peripheral" cisterns or reservoirs of volcanic material, occur- 
ring at very small depths below the surface, and extremely 
sensitive to any variation in the surrounding physical con- 
ditions. Dr. Stiibel regards these "peripheral" reservoirs 
as the base of supply from which present volcanoes derive 
their volcanic material, and he correlates the surface extent of 
volcanic groups and the arrangement of the individual erup- 
tive vents or fissures with the original shape and size of the 
respective areas of primitive, uncooled magma. The force 
which enables it to rise again to the surface resides, according 
to Dr. Stiibel, in the magma itself, and the region of the least 
resistance is the path along which the liquid masses find their 
way to the surface. The conditions of least resistance, he 
adds, are most commonly met with at the limits of different 
kinds of rock. 

The scientific study of the extinct volcanoes, and especially 
the exact petrographical examination of the products of erup- 
tion, has exerted a marked influence on the theoretical 
explanation of volcanic phenomena. It was only to be ex- 
pected that exact knowledge should finally dispose of many 
fanciful hypotheses, such as those which explained volcanic 
action from the burning of coal-seams or petroleum, the 
decomposition of sulphur metals and other substances, from 
electricity, or the local disengagement of vapours. 


Wider geographical and geological knowledge has shown 
the earth's volcanicity to be a phenomenon of universal occur- 
rence which cannot be explained as a result of occasional local 

Descartes had in 1644 suggested that the friction of 
inthrown rock-masses might induce processes of fusion, and 
Franke in 1756 attributed volcanic outbreaks to local 
shearing in the earth's crust. More recently, conversion of 
mechanical work into heat was made the basis of a hypothesis 
by Volger in his book entitled The Earth and Eternity, 
published in 1857. Volger suggested that both earthquakes 
and volcanoes were caused by partial collapse and inthrow of 
rock-material superincumbent upon subterranean cavities. A 
mechanical theory of a somewhat different character was 
proposed in 1866 by Mohr. He supposes that certain 
deep-lying strata in the earth's crust have lost their original 
consistency either by means of chemical decomposition or 
from other causes. If these weaker layers be subjected to the 
pressure of a considerable thickness of overlying rock-deposits, 
and if, as in the submarine areas, they have to bear in addition 
the weight of a vast column of water, they may be crushed, 
heated, and even in some cases melted and ejected at lines of 
crust-fissures. Mohr referred more particularly the submarine 
tuffs to this mode of origin. Pfaff wrote in 1871 a paper 
on "Volcanic Phenomena," in which he opposed Mohr's theory, 
and said that thermo-dynamic action alone could not generate 
sufficient heat to fuse rock-masses. 

The English physicist, Robert Mallet, made the most 
successful attempt to found a mechanical theory of vol- 
canicity. He assumed that the earth's crust, in consequence 
of a slow and protracted cooling of the globe, is now of 
considerable thickness. During the earth's cooling the masses 
contracted as they solidified, and their contraction created 
tangential pressures through the crust. According to Mallet's 
theory, the hotter internal mass of the earth cools and 
contracts more rapidly than the crust, which is in con- 
sequence liable to recurring accidents of incrush and inthrow. 
Tangential pressure is resolved into vertically-acting forces, 
and folds and corrugates the earth's crust, forming larger and 
smaller mountain-chains. Fissures develop along the lines of 
greatest weakness in the crust, and it is chiefly at these that 
the rocks give way for long distances and are crushed and 


crumpled. The work effected by the compression and 
movement of the rocks is transmuted into heat, and under 
local conditions of concentration of the movements or sudden 
cessation and relief of pressure, the temperature of the crushed 
rocks may arrive at the point of actual fusion. If interstitial 
or descending surface-water be absorbed by the glowing 
rock-masses in sufficient quantity, its conversion into steam at 
any moment of diminished pressure may give origin to 
explosive volcanic phenomena at the surface. These are the 
general arguments in Mallet's theory of volcanicity, which 
was strengthened by the author's elaborate series of experi- 
mental researches on the stresses required to crush different 
varieties of rock, and the amount of heat that would be 
produced in each case by this mechanical means. 

Mallet's theory has been contested by Justus Roth in 
Germany and by Poulett-Scrope and Fisher in England. But 
certain ideas in it, such as the steady contraction of the 
earth's nucleus and its tendency to shrink away from an 
unequally yielding crust, have proved distinctly valuable in the 
consideration of the earth's physics, and have been variously 
applied by later authors. 

Most geologists at present look sceptically upon any theory 
which derives volcanic action from the conversion of 
dynamical energy into heat during crust-movements. Present 
opinion associates volcanic phenomena with the primitive 
internal heat of the earth, and supposes rock-magma to be 
embodied in a state of fusion within the earth's mass. This 
was likewise the broad conception of volcanicity which was 
held by the ancient philosophers, and by Athanasius Kircher, 
Steno, Buffon, Dolomieu, Spallanzani, Faujas de Saint-Fond, 
Von Humboldt, Von Buch, Poulett-Scrope, Daubeny, and 

The -actual protrusion ot subterrestrial magmas into the 
earth's crust or at the surface was attributed by Cordier, 
Constant Prevost, and Dana to the cooling of the earth's crust 
and the pressure which it therefore exerts upon the nuclear 
mass. Professor Suess has applied the distinctive term of 
" batholite " to an older massive protrusion of magma 
solidified as coarse crystalline rock in the deep horizons of the 
crust. In 1888, the same geologist in his famous work, Der 
Antlilz der Erde, discusses the conditions which determine 
the particular form of igneous protrusion, whether as deep- 


seated batholites, as laccolites intruded at various horizons 
between the sedimentary deposits, as fissure eruptions, or 
volcanic explosions. He summarises his views in the 
following sentences: "The uppermost peripheral parts of the 
earth's body are held firmly arched in virtue of the tangential 
tensions. Either radial tensions or crust sagging causes a part 
of the earth's body to split away from the outer crust towards 
the interior, and a large cavity or macula forms more or less 
parallel with the earth's surface, lenticular in shape if produced 
mainly by sagging, and wider if due to radial fracture. The 
macula fills with lava ; and if the surface rocks subjected to 
tangential tensions find escape from them in any direction, for 
instance by a folding movement or by the overthrust of 
another mass of rock, then the relieved portion of the arched 
crust which is immediately above the macula sinks into it and 
lava wells forth at the faults and deeper inthrows " (loc. cit., 
vol. i., p. 220). 

Dr. Reyer, in his work Theoretische. Geologic (1888), 
groups batholites, laccolites, domes (Kuppen), and sheets as 
massive eruptions, and distinguishes them from true volcanic 
eruptions associated with fragmentary discharges. At the 
same time he allows that in Mexico, Iceland, and in other 
localities, massive intrusions and outpourings occur in 
combination with typical tuff volcanoes. Reyer contests 
Gilbert's explanation of laccolites as intrusions following the 
bedding-planes of strata ; he regards them primarily as surface 
protrusions contemporaneous with the sedimentary deposits in 
association with which they occur; and with regard to the 
apophyses extending from laccolitic invasions into super- 
incumbent strata, Reyer says they are intrusions altogether 
subsequent to the laccolites. True volcanic mountains must, 
according to Reyer, include tuffs and loose fragmental 
products, but may or may not include lava ; these are piled 
round the orifice and arranged as inclined successive layers. 
The craters are, he thinks, usually the result of explosion ; 
occasionally, however, they arise from inthrow. The larger 
areas of subsidence, on which the volcanic mountains are 
found, appear to have been formed by repeated eruptions. 

It had been recognised by Dolomieu and Spallanzani that 
the violent outbursts from active volcanoes could not be 
entirely due to the pressure of the outer firm envelope of the 
earth upon internal molten material. But, whereas Dolomieu 


Suggested sulphur as the cause of fluxion, Spallanzani believed 
that the expansion of vapours was the main cause of the 
explosive phenomena of eruptions, and Humboldt and 
Poulett-Scrope accepted and extended Spallanzani's view. 
Scrope regarded the elastic vapours as original constituents 
of the earth-magma ; on the other hand, Humboldt contended 
that water had passed down from the surface through fissures, 
had there come in contact with the glowing magma, been 
converted into steam, and absorbed in the magma. The 
majority of later geologists agree with Humboldt's explana- 

Humboldt had chiefly in view the descent of sea-water 
through crust-fissures, as the geographical distribution of 
active volcanoes would suggest, but he by no means excluded 
the likelihood that similar results ensue from the percolation 
of meteoric water through the rocks. The obvious diffi- 
culty, pointed out by Humboldt himself, was whether the 
hydrostatic pressure of the descending column of water could 
overcome the resistance of the vapours at high tension in 
the earth's interior. Bischof and Daubree have shown that 
surface water may, in virtue of capillarity and the pressure of 
its own column, descend into the heated depths of the earth. 
Angelot also concluded that the tension of a column of water 
would at any depth be overcome by the pressure of the 
superincumbent masses of water; in his opinion, the ocean 
is the source of the vapours dissolved in deep-seated magma. 
And Bischof shows that not only, water-vapour but also 
carbonic acid, hydrochloric acid, and other gases imprisoned 
in rock-magma play a considerable part in eruption. 

In more recent geological writings, Reyer has investigated 
the question of supply in reference to the constituents of 
molten magmas, and his conclusions are in agreement with 
those of Angelot, Fourier, and Poulett-Scrope. According to 
Reyer, at the formation of the earth, not only vapour of water, 
but many other gases and liquids were intermixed with the 
material matter of the earth, and these have been preserved in 
it. The continual separation of the less fusible parts from the 
magma is always accompanied by the escape of gases. These 
are absorbed by the liquids with which the magmas are 
soaked, and owing to a relief of superincumbent pressure,- the 
liquids may at any time vaporise and the magma may be 
expelled towards the surface in fluid condition. Experiments 


were made by Hochstetter, Suess, and Reyer on molten 
sulphur and other substances which absorb gases in large 
quantities, and during the process of cooling from the molten 
condition, the escape of the gases was accompanied by 
explosive phenomena. Under certain circumstances, at the 
places of explosion conical-shaped masses formed resembling 
those of volcanic mountains. 

F. Earthquakes. Earthquakes may arise in the solid crust 
or in still deeper horizons of the earth. They accompany all 
the more violent eruptions, but they may take place quite 
independently of volcanic phenomena. Records of earth- 
quakes have been handed down from the earliest times, but 
the classical and mediaeval writers confined themselves to the 
descriptions of the leading natural phenomena, and the 
catastrophes and terrifying effects produced by earthquakes on 
people and animals. 1 

Scientific research of earth-tremors may be said to have com- 
menced in the beginning of the eighteenth century, and had 
already progressed so far that Hoff was able to compile an ex- 
cellent monograph of earthquakes for the second volume of 
his work. Another good account of the phenomena and 
effects of earthquakes was published in Friedrich Hoffmann's 
posthumous works (1828). An essay by Dr. Kries upon the 
origin of earthquakes was awarded a prize at Leipzig in 1827. 
Naumann's Text-book of Geognosy contained a complete 
resume of all the scientific facts about earthquakes known 
before 1850. So exhaustive was Naumann's account that 
Landgrebe could bring forward little additional knowledge 
in his Naturgeschichte der Vulkane und Erdbeben (vol. ii., 


All the earlier writings of the nineteenth century follow 
Alexander von Humboldt in representing earthquakes and vol- 
canoes as different manifestations of the same set of causes. 
Humboldt defined earthquakes as "Reactions of the earth's 
nucleus against the solid crust," and volcanoes as " Safety- 
valves" for the immediate neighbourhood of such disturbances. 
Emil Kluge, who made a special study of the earth-tremors 
and shocks in the years 1850-57, supported Humboldt's 

1 A short historical account of the prevailing views regarding earth- 
quakes which were held by the authorities of antiquity and the Middle 
Ages, will be found in R. Hoernes' Erdbclenkunde, Leipzig, 1893. 


standpoint, and placed great importance on evidences 
of the interchangeable relations subsisting between earth- 
quakes and volcanoes. Naumann contended, in opposition 
to Humboldt's generalisation, that certain earthquakes might 
be termed plutonic, in so far as they occurred independently 
of volcanic influences; Von Seebach also attributed earth- 
quakes in some instances to local disturbances of crust- 
equilibrium, not necessarily associated with the earth's 
volcanicity. Since Humboldt's famous description of the 
Cumana earthquake, great advances have been made in the 
knowledge of the geographical distribution of earthquakes, 
the methods of determining the position of seismic foci, and 
the rate, the intensity, and the mode of propagation. 

One of the most indefatigable bibliographers of earthquake 
phenomena was Professor Alexis Perrey in Dijon. Between 
the years 1841 and 1874 Perrey collected statistics of 
earthquakes extending back for more than fifteen centuries. 
In England, Robert Mallet and his son J. W. Mallet 
published an Earthquake Catalogue for the period i6o5- 
1858; Muschketow collected the data of the Russian and 
Central Asiatic earthquakes ; in Germany, Hoff and Berg- 
haus published in 1841 a catalogue of volcanic eruptions 
and earthquakes, and C. W. Fuchs kept a regular chronicle 
of observations from 1873 to 1885; Volger published a 
careful account of the Swiss earthquakes, together with some 
notes on the periodicity, propagation, and extension of the 

Italy, so frequently the scene of destructive earthquakes, 
possesses in De Rossi, the founder of " underground 
meteorology," a historian of equal rank with Perrey. De Rossi's 
chief work, published 1879-82, comprises his own valuable 
observations and regular records kept for several decades in the 
seismological observatory which he erected at Rocca di Papa 
in the Alban mountains. 

Baratta carefully compiled all the records of the terrible 
earthquake in the year 1627, which devastated the peninsular 
area of Monte Gargano. The Neapolitan earthquake of 
1857 was recorded in a masterly and suggestive paper by 
Mallet. The violent shocks during the last decades of the 
nineteenth century at Belluno (1873), Ischia (1883), and 
Liguria (1887), have been made the subject of a large number 
of publications by foreign geologists and meteorologists. A 


voluminous literature now exists on earthquakes and slight 
tremors experienced in Europe during the last quarter of the 
nineteenth century, special commissions having been appointed 
in most countries to keep a record of observations. 

In Great Britain, Professor James Geikie, Davison, and 
White continue the work of R. and J. W. Mallet, and there is 
no lack of observations in North America, Guatemala, Mexico, 
India, Australia, and Africa. Seismological studies were initiated 
by Dr. E. Naumann and Dr. Knipping in Japan, and the newer 
reports of Dr. Milne, Koto, Sekiya, and others in the 
Transactions of the Seismological Society of Japan } contain full 
accounts of the earthquakes in these localities. 

Of late years very delicate seismometers have been 
invented, by the use of which it has been possible to obtain 
accurate records, not only of violent shocks but of finer 
pulsations and tremors imperceptible to human sensation. 
Cacciatore of Palmero used as a seismometer a shallow shell 
filled with quicksilver, and having a number of notches at 
regular distances round the edge; small cups were placed 
below the notches, and in the event of any movement of the 
shell, the quicksilver escaped into these cups and could be 
weighed as a measure of the intensity of the shock. This 
simple apparatus was replaced by numerous others of much 
more complicated construction, which sometimes applied the 
pendulum, and were sometimes made self-registering by 
specially devised clock-work. Thanks to many ingenious 
inventions, meteorological science now possesses a wealth of 
observations on the frequency, continuance, periodic recur- 
rence, and geographical distribution of earthquakes, as well as 
on the mode of transmission, direction, intensity, rate of 
propagation, and character of the shocks. Geologists have 
concerned themselves more with the destructive effect, the 
surface deformation and geological action of crust-tremors, 
and with the modifying influence exerted by the various kinds 
of rock upon the intensity and transmission of earth- 

Mallet, Von Seebach, Von Lasaulx, and Dutton proposed 
various methods of ascertaining the area of impulses during 
an earthquake. Both Mallet and Seebach concluded from 
geometrical methods that the seismic focus was at a 
comparatively small depth below the surface, but this result, so 
far from having been confirmed, seems to be contradicted by 


Whitney's observations in California, by Wynne's in the Punjab, 
and by Heim's in Switzerland. 

Perrey's long historical catalogue of earthquakes was 
intended in the first instance to determine how far earth- 
tremors had been encouraged by the particular times of the 
day, or seasons of the year, or by the disposition of the earth 
with reference to other heavenly bodies. The results are not 
altogether satisfactory, for although they prove greater 
frequency of earth-tremors in winter and autumn than in 
other seasons, no definite law can be induced. Neither do 
the statistics give any confirmation of the idea that the 
occurrence of earthquakes may have some connection with 
meteorological conditions. On the other hand, they led 
Professor Perrey to conclude that an explanation of earthquakes 
might be found in the varying attraction of the moon at its 
different phases. 

He supposes the earth's crust to be as uneven on its inner 
concave surface towards the nucleus as upon its outer surface ; 
that under the attraction of the moon the hot nucleus swells 
upward in wave-like form and presses against the weakest 
parts of the crust, with the result that the terrene impulse is 
transmitted through the crust as an earthquake. 

Dr. Rudolf Falb in 1869 independently formulated a theory 
of earthquakes similar in character, but more fully elaborated 
than that of Professor Perrey. Dr. Falb connects high tidal 
waves of the earth's magma with the attractions exerted upon 
the earth by the sun, the moon, and other .heavenly bodies, 
and he therefore thinks it possible to foretell from astronomical 
calculations "critical" days or periods on which violent 
seismic disturbances will take place. A general connection 
between solar and lunar attraction and the occurrence of 
earthquakes is accepted by a considerable number of 
astronomers and geologists, amongst others, by J. Schmidt, 
C. F. Naumann, Von Lasaulx, Pilar, and others. But several 
authors have disputed Dr. Falb's theory. One main conten- 
tion is the uncertainty regarding the actual condition of the 
earth's nucleus ; many physicists and geologists now believe 
that the nucleus is practically solid, and that molten rock- 
magma can only be present under certain definite conditions 
of depth and pressure, and is necessarily of limited distribution 
in the earth's mass. 

Friedrich Hoffmann had distinguished different kinds of 


earthquakes according to their field of action as succussive or 
vertical, undulatory or wave-like, and rotatory or whirled. 
At the present day, earthquakes are usually classified as 
central and linear; in the case of "central" earthquakes the 
undulatory movements radiate from a seismic focus towards 
all directions; in the case of "linear" earthquakes, the 
movements are limited to long strips of the crust. Von 
Seebach termed the subterranean origin of an earthquake the 
" seismic centre " ; the median point at the surface within a 
region of earthquake shock he termed the "epicentrum" at 
this point the shock manifesting itself chiefly by up and down 
motion ; and to the imaginary lines drawn through all points 
simultaneously affected by the shock, he gave the name of 
"homoseisms" or "isoseisms." But it has to be remembered 
that a definite central point of origin has only been determined 
in a few cases. Generally the seismic centre or focus has 
been ascertained to be in point of fact an underground area 
from which concussions are propagated vertically along a 
large number of parallel lines, which Mallet has called 
" Seismic Verticals." Undulatory impulses are also transmitted 
obliquely through the surface, the intensity of the shock at the 
surface diminishing in proportion as the angle of emergence 
increases. In the case of the Agram earthquake in 1880, a 
large surface area was affected by vertical movements of 
almost equal intensity, showing that the underground focal 
area was of considerable extent. 

The leading geological authorities now associate earthquake 
shocks with manifestations of volcanism, crust collapse, or 
tectonic crust-movement. Earthquakes as a rule precede or 
accompany the eruptions of active volcanoes, but they often 
occur in volcanic districts when there is no actual discharge 
from volcanic vents. The earthquakes which have been 
directly traced to crust subsidences were of small extent and 
intensity. And it is now widely accepted that most earth- 
quakes which occur in non-volcanic districts are originated by 
dislocations and movements in the earth's crust. 

In two suggestive papers (1873-74) on the Earthquakes of 
Lower Austria and Southern Italy, Professor Suess showed 
conclusively that earthquakes occur along the lines of tec- 
tonic movement in a mountain-system, and quite irrespective 
of any volcanic phenomena. Hoernes contributed several 
interesting papers on tectonic tremors, demonstrating by 


specific examples the frequency of earthquakes along narrow 
tracts or over areas which have been the seat of important 
crust-movements of displacement, fracture, or subsidence. 
Toula proposed the distinctive name of "dislocation earth- 
quakes" to such as accompanied the grander movements in 
the earth's crust. 

Gilbert in California, Griesbach in Beloochistan, Koto in 
Japan, and other observers have proved the origin of extensive 
fissures at the earth's surface as a consequence of recent 
earthquakes. Permanent changes in the surface conformation, 
especially subsidences, have very often been reported as a 
chief factor in the catastrophes caused by earthquakes. In 
the fearful earthquake at Lisbon, the quay sank into 
the sea with all the ships anchored in it and thousands of 
people on its margin. During the Calabrian earthquake, in 
the year 1/83, more than two hundred lakes and morasses 
were formed. In the year 1819, according to Lyell, an 
earthquake at the eastern river-mouth of the Indus converted 
an area 2000 square miles in extent into a lake ; on the 
Mississippi flats, in China, Syria, and Chili, earthquake 
inthrows have been recorded. 

It has, however, rarely happened that the ground has been 
elevated in consequence of the passage of an earthquake. 
The best known accounts of elevations come from Chili, and 
were accepted as trustworthy by no less an authority than 
Charles Darwin ; Professor Suess regards them as of doubtful 
integrity, and C. W. Fuchs affirms that since earthquakes and 
their phenomena and consequences have been observed with 
scientific accuracy, not a single case of ground-elevation has 
been authoritatively recorded. 

G. Secular Movements of Upheaval and Depression. The 
study of the sedimentary deposits of past geological epochs 
reveals conclusively that vast changes have repeatedly taken 
place in the distribution of land and sea upon the face of the 
earth. But it is difficult to determine what changes are now 
in progress, whether certain parts of the earth's land surfaces 
are being at present elevated or depressed, or whether oceanic 
variations are accomplishing changes in the relative level of 
land and sea. It seems almost impossible to record slow 
movements in the interior of the continents, and the 
topographical maps render little assistance in this respect, as 


it is only a century since measurements of height have been 
taken in sufficient number and with sufficient accuracy to 
afford secure data for comparison. For geological processes a 
hundred years is a period of as small significance as a single 
second in the history of mankind. 

It is easier to determine variations of level at sea-coasts, 
but even there it is often doubtful whether a change of 
relative level is due to displacements of the land or of the 
ocean ; and the observer has to be careful not to mistake for 
secular movements any of the effects of sedimentation in 
heightening the land, or of marine erosion and subaerial 
denudation in breaking down the coast. The occurrence of 
submerged forests and beds of peat, old roads and other 
human structures on the sea-floor are among the more secure 
evidences of a depression of the land or uprise of the water. 
On the other hand, remains of harbour and pier con- 
structions, and fragments of vessels found at a height above 
the existing sea-level, or at some distance inland, give evidence 
of a secular movement of land-elevation or retreat of the sea 
within historic ages. Former coast-lines and terraces can 
sometimes be. identified many hundred feet above the present 
surface of the ocean. The exposure of delta deposits is 
usually regarded as a sign of land elevation, whereas long 
narrow fiords occurring as the continuation of river-valleys 
towards the sea, are regarded as proofs that a coast is 
undergoing subsidence. 

The oldest direct observations on relative changes of level 
were made in Scandinavia. Hjarne observed in 1702 that the 
Swedish coasts were frequently extended in consequence of a 
retreat of the sea, and Celsius and Linnaeus afterwards made 
investigations on the rate of retreat by means of boundaries 
and marks on the rocks at Gefle and Kalmar. Celsius in 1 743 
read his memorable paper at the Swedish Academy of Science, 
in which he argued that the volume of water in the ocean was 
diminishing. He calculated the sinking of the ocean surface- 
level at forty-five inches in a century. Linnaeus supported 
the views of Celsius, but Bishop Browallius (1756), E. D. 
Runeberg, and the Danish scientist, Jessen (1763), opposed 
them. E. D. Runeberg argued that the changes on the 
Swedish coast were due to elevation of the land in consequence 
of earthquakes. 

The Scottish mathematician, Professor Play fair, in 1802 


raised an important objection to the theory of Celsius by 
pointing out that if the changes were really due to the lowering 
of the ocean-surface, the diminution should, according to 
hydrostatic laws, take place quite uniformly, and this was 
apparently not the case. Playfair therefore attributed the 
changes to an elevation of the land in consequence of subter- 
ranean forces. Leopold von Buch also formed the opinion 
that the Swedish coasts were rising, but neither in his work in 
1807, nor in Karl von Hoff's historical and critical reviews in 
1834, was any explanation suggested as to the causes of the 

The Stockholm Academy appointed a Commission to inquire 
into all the evidences, and the reports in 1820 and 1821 
entirely corroborated the scientific account of a general 
extension of large coastal tracts. The upraised mussel-beds 
near Uddewalla, on the west coast of Sweden, and the raised 
beaches with marine shells in Norway, had been cited by 
Buch, Brongniart, and Lyell as proofs of land elevation. 
Yet the chemist, Professor Jacob Berzelius, in 1835 adhered 
to the older view; he connected the changes along the coast 
with sinking of the sea-level in consequence of the cooling of 
the earth and contraction of the crust. In 1837, Professor 
Keilhau in Christiania collected all the observations that had 
been made on coast movement in Norway, and calculated from 
them that the land had risen 470 to 600 feet since the Diluvial 

A French expedition was sent to Scandinavia and Lapland, 
and Dr. E. Robert, the geologist attached to it, was enabled 
to add to Keilhau's summary a number of supplementary 
observations in Finland and Lapland. It was thus proved 
that raised beaches and terraces extended throughout all the 
northern part of Scandinavia. Bravais, another member of 
the French expedition during a prolonged stay in Finland, 
followed the remains of former coast-lines between the Alten 
Fjord and Hammerfest, and in his papers published 1842-43 
he described in the Alten Fjord two successive terraces which 
were not parallel with one another, but converged towards the 
coast and showed several variations of height at their different 
parts. This observation was declared by Naumann in his 
text-book to be incontestable proof that the coast had been 
elevated. Considerable doubt, however, was thrown upon 
Bravais's observations a few years later by Robert Chambers 


in an important work on Ancient Sea-Margins. The Chris- 
tiania Professor, Theodore Kjerulf, in 1871-73 also questioned 
some of Bravais's observations, although he in no way dis- 
sented from the opinion that the land had been elevated. 
Professor Sexe in Christiania sought an explanation of the 
phenomena in glacial action, but H. Mohn and K. Pettersen 
in several papers published between 1870 and 1880 refuted 
this suggestion, and added many new data in confirmation of 
land elevation. Dr. Pettersen showed that the Norwegian raised 
beaches and terraces occurred at higher and higher levels the 
farther inland they were found, and that the highest platforms 
were situated at the upper end of the deep fjords. 

The Swedish geologist, De Geer, confirmed this observation 
both in Norway and Sweden, and drew up a chart of curves con- 
necting all the raised beaches of the same height. These curves 
he termed " iso-anabases," and found that they formed a series 
of ellipses whose major axis almost coincided with the water- 
shed between Sweden and Norway. De Geer concluded that 
Scandinavia had been slowly upheaved since the Ice Age, the 
extent of the upheaval exceeding 600 feet in the central areas of 
the country. But he thought certain facts indicated that there 
had been a slight movement of subsidence between a period of 
maximum upheaval and the present epoch of elevation. While 
it was in Scandinavia that crust movements now in progress 
first attracted the attention of scientific men, keen interest was 
aroused in Scotland by analogous examples of upraised mussel- 
beds and beaches (the " parallel roads "). As early as 1806, 
Jameson had observed deposits containing the shells of recent 
molluscs at some height on the shores of the Firth of Forth 
and the Firth of Clyde, but published no account of them 
until 1835. Afterwards several geologists examined them, 
amongst others Prestwich and Robert Chambers. The 
traces of ancient sea-margins far inland were first recog- 
nised by MacCulloch, and have since been described by 
Charles Darwin, Agassiz the elder, Murchison, Buckland, 
Lyell, and more recently by J. Geikie. Almost without 
exception all observers agree in regarding them as proof of 
recent elevation of the land. 

Similar evidences of elevation occur in Ireland, England, 
Finland, on the coast of the White Sea, on the islands of 
Spitzbergen and Novaia Zemblia, on the coasts of Siberia, 
Greenland, on the eastern and western coasts of North 


America, in Patagonia, the Argentine Republic, Chili and 
Peru, and at the southern extremities of Australia and 

Darwin, in founding his Coral-reef theory, assumed that a slow 
subsidence had taken place over a vast region of the Pacific 
and Indian Oceans. In spite of a very large number of data, 
however, it has not been possible to formulate any definite law 
of secular variations. Movements of elevation and depression 
are reported in various latitudes, and are frequently known to 
take place in opposite senses at localities adjacent to one 
another. When Dana in 1849, from his observations in the 
Pacific Ocean, concluded that elevation was in progress in the 
region around the North Pole, and subsidence in the areas 
near the Equator, he formed his opinion upon insufficient 
data. The general truth has, however, been established, that 
relative changes of level are still in progress along many of the 
coast-lines, and that since the Diluvial epoch dislocations have 
been produced, measuring 300-1500 feet. In many cases 
these movements are slowly and imperceptibly accomplished, 
in others they occur with convulsive suddenness. Sartorius 
von Waltershausen in 1845 distinguished the former as 
Secular, the latter as Instantaneous fluctuations of ground- 

Von Humboldt and Von Buch had directed attention 
to local movements of land in connection with volcanoes and 
earthquakes, and the example of this character most frequently 
cited in literature is the temple of Serapis at Pozzuoli, in 
the Bay of Naples. The columns of the ruined portico are 
marked by the borings of a marine mollusc at a height of 
thirteen feet above the present surface-level of the Bay. In 
1803, Breislak in the French edition of his text-book explained 
the phenomenon on the hypothesis that the Serapeum had 
subsided and had remained for a period stationary at the 
water-level indicated on the pillars by the mollusc borings, but 
that afterwards a period of emergence and uprise had succeeded. 
This explanation was strongly opposed by Wolfgang von 
Goethe. The great poet would not listen to any arguments 
in favour of oscillations of level; in his opinion, the former 
submersion of the temple had been due to an enormous flood. 
Breislak's view has, however, been supported by several 
leading British scientists, Babbage, Forbes, Poulett-Scrope, 
and Charles Lyell. The excellent treatise published by 



Babbage in 1834 has proved a reference work of permanent 
value. Lyell used it freely for his discussion of the subject 
in his Principles. Continental authors of repute, Hoffmann 
(1833), Scacchi (1849), also accepted the explanation of alter- 
nating movements, and the Serapeum became a recognised 
example in the text-books of "instantaneous" change of level. 

Antonio Niccolini made observations for several decades, 
and wrote, between 1838 and 1846, a series of papers in which 
he contended that the submersion of the Serapeum had not 
been due to any movement of the land, but to a rise in the 
water-level of the ocean. Professor Suess has arrived at the 
same conclusion as Niccolini; he points out that the changes 
of level at Pozzuoli were limited to the area of the Phlegrean 
volcanic cones, and argues that after a slow rise of the water- 
level throughout many centuries, there came during, or 
immediately after, the eruption which formed Monte Nuove 
(1538), a sudden lowering of the water-level, so that the 
temple ruins were once more fully exposed. 

Other cases of instantaneous uprise have been reported from 
the western coast of South America. The first account 
appeared in a letter from a lady, Mrs. Maria Graham, to the 
Geological Society of London. The letter relates how, after 
the Valparaiso earthquake in November 1822, a long strip of 
the coast of Chili rose three or four feet above the sea-level. 
The German traveller, Poppig, heard confirmatory evidence 
from the fishermen of the district when he visited the Bay of 
Concon in 1827. Charles Darwin and Captain Fitzroy 
witnessed, in 1835, a violent earthquake in Chili, and they 
reported local elevations of eight or nine feet along disloca- 
tions that formed in the district of Concepcion and Valdivia. 
Darwin also observed raised beaches and terraces at various 
heights on the coasts of Chili, some of them 1,500 feet above 
sea-level, and he came to the conclusion that sudden eleva- 
tions of land had followed the earthquakes so frequently 
associated with volcanic activity in that neighbourhood. Upon 
the basis of his direct observations in Chili, Darwin founded 
his bold theory of the uprise of continents and mountain- 
systems by successive sudden elevations due to volcanic 

Ever since oscillations of level have been observed, there 
have been differences of opinion regarding the cause or causes. 
Strabo doubted as little in the elevation of islands, mountains, 


and portions of the continents, as in the collapse and sub- 
mergence of larger and smaller areas of the land. Athanasius 
Kircher gave circumstantial descriptions of sunken islands 
(Atlantis), and of lands raised from the ocean-floor. In the 
eighteenth century, De Maillet and Buffon ascribed changes 
of surface conformation to gradual diminution of the ocean 
volume, while Lazzaro Moro tried to explain the double 
aspect of emergence of land and ascent of the water-level by 
means of volcanic catastrophes. The Swiss investigator, J. G. 
Sulzer, in 1746 suggested the possibility that the position of 
the earth's centre of gravity was affected by the variable dis- 
tribution of surface material; and Justi, in 1771, believed in 
"wanderings " of the Pole. 

In 1702, the Swedish physicist Hjarne had introduced the 
method of direct observation by having marks hewn on the 
rocks of the coast, and thus paved the way for the definite 
knowledge obtained in the case of the Scandinavian move- 
ments. Scientific opinion then wavered between two chief 
parties, the one believing with Celsius in the lowering of the 
ocean-level; and the other and stronger party following Hutton, 
Playfair, Buch, Lyell, and others in ascribing the relative changes 
of level to upheaval of the land associated with subterranean 
volcanicity. Bischof, although he expressed in the chapter 
on " Heat " his agreement with the Huttonian Theory of 
Expansion, afterwards attributed secular movements more 
especially to alternating expansion and diminution of volume 
produced in deep-seated rocks by chemical transformations. 
Following this direction of thought, Volger, Mohr, and Vogt 
thought that the originally sedimentary rocks of Scandinavia 
had been transformed into crystalline rock, and had under- 
gone an expansion of volume during the process of crystallisa- 

The French mathematician, Adhemar, was the first scientist 
who, in seeking an explanation for crust-movement, considered 
the earth in its cosmogenetic relations. He regarded the 
influence of the earth's internal heat as quite irrelevant to the 
climatic conditions at the earth's surface; these he attributed 
wholly to the action of the sun's heat, and investigated the 
varying positions of the earth relatively to the sun, with a view 
to explaining the recurrence of Ice Ages and also the associated 
periodic rise and retreat of the ocean. Research in this 
direction thirty years later was greatly advanced by James 


Croll and J. H. Schmick. These observers also supposed that 
periodic attraction of the ocean-water now towards one 
hemisphere, now towards the other, caused variations of climate 
and fluctuations of level. But if this hypothesis be correct, 
there ought to be extensive regions of depression or elevation; 
local movements in opposite senses, and especially oscillatory 
movements, are excluded. Dana's assumption of a widely- 
extended movement of elevation towards the North Pole has 
been supported by Sir Henry Howorth, whose idea is that the 
land is rising at both the Poles and contracting at the Equator. 

From the actual distribution of the geological formations, 
Dr. Trautschold inferred the probable conditions of the earth's 
surface during past epochs, and argued that the volume of water 
in the ocean has gradually been diminishing. As immediate 
causes of diminution, he specified the accumulation of masses 
of snow and ice on land areas, the formation of inland seas 
and rivers, the absorption of water in consequence of the 
hydration of rock-forming minerals, and the consumption of 
water in the organic world. Dr. Trautschold by no means 
contested movements of crust-elevation, but thought many 
cases of so-called secular upheaval explicable by the lowering 
of the ocean-level. 

Professor Eduard Suess introduced quite new ideas into the 
discussion of secular movements. In 1875, i n ms work on the 
origin of the Alps, he attributed the elevation of the Scandi- 
navian Peninsula to the upward arching of a wide fold ; but in 
later works, when he entered into a full and critical treatment 
of the whole question, he came to the conclusion that there 
were no movements of the crust in vertical senses, with the 
exception of those which are accomplished indirectly in the 
course of crust-folding. Suess then proposed a neutral termin- 
ology to express changes of level; instead of "elevation" and 
"subsidence" he now speaks of "positive" movements when 
a coast-line appears to rise, and " negative " movements when 
it appears to sink. His first elucidation of these views in 1880 
culminated in the statement that the phenomena of so-called 
secular upheaval and depression had their origin in continuous 
changes in the liquid envelope of our globe. Suess could 
offer no explanation of those changes, which sometimes at one 
period might amass the ocean-water towards the equatorial 
zones, at another withdraw it towards Polar regions. He indi- 
cated as a possibility that they might have some connection 


with variations in the earth's rotatory force, and consequently 
in the length of day and night, or with any incongruity between 
the earth's centre of gravity and the centre of form. 

Professor Penck agrees with Suess in the leading principle 
that secular variations are due, not to crust-movements, but to 
fluctuations of sea-level. He doubts, however, the possibility 
of the equilibrium between land and water being disturbed by 
general variations of the earth's gravity. He traces all changes 
of level in maritime tracts of land to local re-distribution of 
rock-material and consequent local alteration in the attractive 
force exerted by the land upon the water-surface. Re-dis- 
tribution may be produced by crust-folding, by the denudation 
of adjoining continental areas by the sedimentation of organic 
and inorganic deposits on the sea-floor, and most of all, in 
Professor Penck's opinion, by the piling-up of colossal masses 
of ice in particular regions. The American geologist, Mr. 
Upham, has arrived, on independent grounds, at similar 
conceptions of variation in the sea-level, although he at the 
same time believes in the actual upheaval of land areas. 

The whole question is again discussed by Suess in the 
second volume of his work, Das Antlitz der Erde. This 
volume describes and compares the coast-line of the Atlantic 
and Pacific Oceans, passes in review the distribution of the 
oceans in all past geological epochs, and gives a complete 
account of all relative changes of level between land and water 
within historic time. The many sources of error and the 
insufficiency of data are noted; and the several causes which 
might have influenced the surface of the ocean are carefully 
elucidated. Professor Suess adheres firmly to his view that 
secular movements of elevation of land have been without 
significance in determining the grander forms of the earth's 
surface, and take place at the present day very exceptionally, 
and only as local phenomena. He depicts a shrinking crust 
or lithosphere, which as it contracts carries with it the immense 
body of water on its surface. According to Suess, episodal 
crust-subsidences have determined the form and position of the 
ocean-basins at different epochs of the earth's history, and 
have been accompanied by the corresponding widely-extended 
negative movements of the ocean. The existing oceans repre- 
sent areas whose subsidence may have occurred in various ages, 
and whose boundaries are marked by lines of crust-fracture. 
Bearing in view the vast extent and the uniformity of those 


negative movements, Professor Suess thinks it impossible to 
explain them by local ground-elevations; they must be assigned 
to physical causes of universal significance. 

In addition to the general movements of the water-surface, 
there have been oscillatory fluctuations of level limited to 
smaller districts. Local sinking of level is probably due to 
submarine eruptions or any increase of the deposits on the sea- 
floor ; or it may be connected with continental denudation and 
the smaller attractive power exerted on the water by adjoining 
land. Ascending movements have their origin probably in 
periodic and alternate heaping of the ocean-water at the Poles 
or at the Equator, or in local expansion of the water surface 
under the attraction of newly-formed land or ice masses. 

The tangential folding of the earth's crust, to which Suess 
attributes the origin of mountain-systems, exerts, in his opinion, 
only a small and indirect influence on the sea-level. The uprise 
of continents takes place only as a result of cmst-inthrows 
and consequent depression of the sea-level. In the upraised 
land, as the gradients of rivers become greater, the transporta- 
tion of sediment is likewise increased; enormous masses of 
material gather close to the coast, and the weight of these 
depresses the sea-floor, inducing further , positive movement. 
All the reported facts which might seem to countenance the 
conception of upheaval of the land are subjected by Professor 
Suess to careful criticism, and found by him to be for the 
most part untrustworthy as direct evidence of land movements. 
In so far as Suess has referred the grander secular movements 
to subsidence of the water-level associated with crust 
shrinkage, his results will commend themselves to all students 
of crust-physics. But his work cannot be said to have 
arrived at a solution of the causes of local oscillatory 
movements. Suess himself concludes his discussions with 
the somewhat mystic-sounding sentence: "As Rama looks 
across the ocean of the universe, and sees its surface blend in 
the distant horizon with the dipping sky, and as he considers 
if indeed a path might be built far out into the almost 
immeasurable space, so we gaze over the ocean of the ages, 
but no sign of a shore shows itself to our view" (Das 
Antlitz der Erde, ii. 703). 

Notwithstanding the strong arguments directed by Suess 
against secular upheaval of land areas, many geologists believe 
in an independent upward movement of certain parts of the 


solid crust. Professor Erich von Drygalski, who as an explorer 
on the Northern Coast and in Polar regions is no less distin- 
guished as a mathematical physicist than as a geologist and 
geographer, holds the opinion that phenomena of upheaval and 
subsidence can be produced by alternating decrease and increase 
of the temperature at the earth's surface. Professor Bruckner, 
the chief Swiss authority on fluctuations of level, does not agree 
with Nordenankar and Suess that the positive movement of 
Scandinavia may be explained by the gradual depression of 
the Baltic Sea. On the German coasts of the Baltic, where 
the variations of the water-level, as in the case of inland seas, 
depend upon the amount of rainfall and the volume of 
inflowing river-water, the oscillations leave horizontal lines. 
But on the Swedish coasts the former coast-lines do not run 
horizontally, they slope obliquely upward, thus affording 
evidence, in Bruckner's opinion, that the movement had been 
an unequal crust-movement. Several geologists who have more 
recently examined the Swedish coasts, Leonhard Holmstrom 
(1888), Sieger (1893), and Kayser (1893), arrived at the same 
result and supported the view of continental oscillations. 

Penck has modified his previous opinion and now accepts 
independent crust-movement as a concomitant factor in 
elevating or depressing a coast-line. Bruckner goes farther, he 
argues that all the present littoral displacements, which are 
not directly associated with volcanic activity at the surface, 
are explicable only if we accept crust-movement as an essential 

H. Older Dislocations in the Earth's Crust Tectonic 
Structure and Origin of the Continents and Mountain- Chains. 
The terrestrial movements and changes which have been 
observed within historic times give us but a faint indication 
of similar phenomena in earlier periods of the earth's history. 
On studying the dislocations which occurred in past geological 
epochs, we arrive at a clearer conception of consummated 
movements and their effects, we perceive how ancient 
strand displacements have culminated in the complete 
submersion of islands and continents, or in their emergence, 
and how mountain-systems have arisen in the neighbourhood 
of ancient zones of crust-disturbance and weakness. 

With the exception of the observations of Steno, which 
were far in advance of his time (ante, p. 26), the scientific 


and methodical investigation of the earth's crust may be said 
to have begun towards the end of the eighteenth century. 
The careful sections of the Thuringian district prepared by 
Lehmann and Fuchsel initiated a new direction in crust- 
physics, and fore-shadowed* the special work undertaken by 
stratigraphical research in the present day, to find out the 
actual distribution of the rocks in the ground so far as they 
are at present exposed to view, and if they do not occur in 
undisturbed horizontal succession, to determine what dis- 
placements they have suffered, and reconstruct as nearly as 
possible a true mental picture of the sequence of events, the 
original distribution of the various sediments in time and 
place, the subsequent movements secular or paroxysmal, and 
the character of the resultant deformation of rock-particles 
and rock-masses. 

Werner and his scholars contributed to field research many 
of its precise terms and methods. They examined the rocks 
with respect to strike and dip ; alternations of strata ; mutual 
stratigraphical relations in vertical and horizontal directions; 
the displacements effected along fault-lines; upheaval, curva- 
ture, bending and folding of rocks. The terminology which 
they applied very often betrays the close connection which 
existed between the mining industry and the beginnings of 
stratigraphy. The mines, the minerals, and any evidences of 
rock-displacement discovered during the mining operations 
were the sources of knowledge from which Werner taught, and 
as his scholars gradually extended their field of vision, and the 
glance of a Humboldt or a Leopold von Buch became world- 
wide, the early impressions and familiar terms of student days 
were grafted into the more ambitious conceptions and general- 
isations with which such men enriched the systematic study of 
the earth's crust. Many mining terms have thus been adopted 
into geological literature, although the original significance has 
been in some cases considerably modified. 

Pallas and De Saussure gave the first more exact accounts of 
the structure of mountain-systems, and early in the nineteenth 
century important advances were made by the investigations of 
Ebel, Studer, Escher, Elie de Beaumont, and others in the 
Alps, those of Voigt and Heim in the Thuringian Forest, of 
Merian and Thurmann in the Swiss Jura Chain, of De la 
Beche in Cornwall and Devonshire, of Sedgwick and Murchison 
in Wales, and of the brothers Rogers in Pennsylvania. The 


conceptions of geologists regarding the structure of mountain- 
systems altered as their knowledge of stratigraphy increased ; 
the stages of progress may be judged by a comparison of the 
text-books of geology published in the successive decades of 
the nineteenth century. 

The text-books of the Wernerian School were mostly 
ignorant of the complicated structure of mountain-systems ; 
inclined strata were assumed to have originated in the inclined 
position. Their teaching on structure was based exclu- 
sively upon observations in plains, hill districts, and mines. 
Geological sections of mountains and plains appear in the 
work of Conybeare and Phillips, and an ideal section of 
the earth's crust in Buckland's Text-book of Geology (1836) 
became the model for a number of similar attempts. Lyell's 
Principles and Elements of Geology, like the majority of the 
text-books in the first half of the nineteenth century, treated 
the structural relations of the earth's crust somewhat meagrely. 
Naumann, in his Lehrluch der Geognosie (1850), was the 
first author who devoted a special chapter to " Geo-Tectonics," 
and he comprised in it practically everything which had been 
established in this domain of geology. 

As the interest in tectonical relations developed, the 
questions of the earth's configuration began to be studied 
from a more intelligent standpoint. Previous centuries had 
offered only speculative literary matter on this subject. Steno 
certainly had as early as 1669 appreciated the fundamental 
doctrines of configuration ; upon the basis of his own re- 
searches in Tuscany, he had explained the forms of mountains 
and valleys as the results partly of crust compression and 
fracture, partly of the upheaval of stratified deposits, partly 
of the accumulation of volcanic material. Descartes, Leib- 
nitz, and Buffon attributed the origin of ocean-basins, con- 
tinents, and mountain-system^ to fracture and wrinkling of 
the solid crust, and to withdrawal of the surface waters into 
subterranean cavities. Hooke, Vallisnieri, Lazzaro Moro, 
Needham, and others thought volcanic forces had upheaved 
the continents and mountain-systems. 

Inthrows, subsidences, wrinkling of the crust in virtue of 
the earth's contraction, and upheaval by subterranean forces 
have long been recognised as the principal factors in 
determining surface conformation, and re-appear in modern 
theories with various modifications and applications. 


The founder of the newer theories of upheaval was without 
doubt James Hutton, the Scottish geologist. According to 
Hutton, the earth's internal heat caused the rocks to expand 
and to find relief by bulging upward; thus portions of the 
earth's surface rose above sea-level and formed continents and 
mountains; volcanoes provided a means of exit for the hot 
vapours and molten masses of rocks, and prevented the 
excessive expansion and upheaval of the earth's crust. 
Although Hutton's theory of expansion and elevation was at 
first little considered, a number of observers like Fichtel and 
Pallas arrived at similar conclusions from independent re- 
searches, while De la Beche, Babbage, Lyell, and Poulett-Scrope 
accepted the theory and extended it in various directions. 

Leopold von Buch was an enthusiastic supporter of the 
Huttonian theory. In the year 1812, J. L. Heim had 
assigned to basalt an important role in the elevation of 
mountain-chains. Von Buch ten years later, after his studies 
in South Tyrol, became convinced that the dolomite was an 
altered limestone, the transformation having been effected by 
the action of volcanic magnesian vapours during the protrusion 
of augite porphyry. From the stratigraphical relations of the 
sedimentary rocks and their association with the augite 
porphyry, Buch developed his well-known theory that the 
whole Alpine system followed the direction of an enormous 
fault, through which augite porphyry had locally escaped at 
the surface, and had elevated, tilted, and folded the 
neighbouring rocks. The results obtained in South Tyrol 
were then applied to Thuringia and the Harz, and finally the 
hypothesis was expressed that all mountain-chains had been 
upheaved by augite porphyry. 

The disciples of Buch found in the theory of eruptivity 
and consequent disturbance of strata a complete explanation 
of all possible complications of crust-deformation, and for a 
time the upheaval of mountains was ranked as a volcanic 
phenomenon. Poulett-Scrope in 1825, in his work On Vol- 
canoes^ supported Hutton's Plutonic doctrine, and entered into 
an elaborate investigation of the ascent of intrusive granite and 
porphyritic masses in relation to the tectonical effects produced 
upon the different kinds of rock-strata which might happen to 
be in the neighbourhood. 

A Swiss geologist of note who shared Buch's views on 
mountain-upheaval was Bernhardt Studer; he explained the 


granitic and gneissose masses of rock in the highest chain of 
the Alps as the chief "centres of elevation" during Alpine 
upheaval, and applied to them the distinctive name of Central 

Some remarks of Buch about the direction of the mountain- 
systems in Germany were destined to bear greater fruits than 
that thinker at the time realised. His paper On the 
Geognostic Systems of Germany, published in 1824, noted that 
four systems of strike had to be distinguished, the Netherlands 
or North-West system, the North-East system, the Rhine or 
North-South system, and the Alpine or East-West system. 
This observation of Buch gave the impulse to the works of a 
gifted French geologist. 

Elie de Beaumont 1 belonged to the most enthusiastic ad- 
herents of the Volcanist doctrines. Many years of geological 
surveying in the Vosges and Ardennes mountains, in the 
mountains of Provence, in the Dauphine and at Mont Blanc, 
had shaped in his mind new ideas about the origin of the 
mountains, and in 1829 he made these known in the Annales 
of the French Academy. Mountain-structure is discussed in 

1 Leonce Elie de Beaumont, born on the 25th September 1798, at 
Canon (Dep. Calvados), belonged to a noble family of Normandy. His 
preparatory studies were conducted in the Henri IV. Seminary in Paris, 
and after a brilliant course in the Polytechnic School in Paris, he entered 
the School of Mines in 1819, to devote himself to Mineralogy. Here he 
attracted the attention of the Professor of Geology, Brochant de Villiers, and 
together with his fellow-student Dufrenoy accompanied the Professor in 
1822 to Great Britain, in order to become acquainted with the mines in 
that country and to get insight into the British methods of geological sur- 
veying. Elie de Beaumont and Dufrenoy then set to work in 1825 to 
prepare a geological map of France. At first they worked under the 
direction of Brochant de Villiers, afterwards they continued independently, 
and in eighteen years the map was completed. Its publication exerted a 
powerful influence on the whole development of geology in France, and 
secured for the two authors a. distinguished place amongst their scientific 
contemporaries. In 1827, Elie de Beaumont was elected Professor of 
Geology in the School of Mines, and in 1835 he succeeded his patron, 
Brochant de Villiers, as General Inspector of Mines. He held in addition 
several high governmental offices, and used his influential position invariably 
for the good, of his colleagues. After the conclusion of the general geo- 
logical survey of France, Elie de Beaumont directed the special geological 
survey until his death on the 2ist September 1874. The geological fame 
of Elie de Beaumont rests on his admirable field-work and his writings con- 
cerning the age and origin of mountain-systems. An account of his life and 
his contributions to science was published by Sainte-Claire Deville at Paris 
in 1878. 


a short passage towards the close of this treatise. Brief 
although they are, the remarks on the influence of the slow 
cooling of the earth on surface conformation and the origin of 
furrows and fissures, are at once recognised by a reader of the 
present day as the starting-point of our modern views on 
mountain-structure. Favourable reviews by Brongniart and 
Arago helped to spread the fame of the young geologist, and 
to win rapid recognition for his work. 

It was not until 1852 that Elie de Beaumont discussed the 
details in full, and gave expression to his conceptions in his 
three-volume work On Mountain- systems. He points out that 
in virtue of the continued cooling of our planet the radius is 
shortened and the crust is affected by a general centripetal 
movement. Delesse had calculated 1,340 metres as the amount 
by which the earth's radius had already been shortened; in 
other words, the earth's crust in the course of the geological 
epochs had approached the earth's centre by a distance about 
equal to the height of Chimborazo or the Himalayas above 
sea-level. As the more rigid crust tried to subside and accom- 
modate itself to the contracting molten mass of the nucleus, 
inequalities and excrescences formed ; or if the tension became 
too great a sudden rupture of the crust ensued, and the lateral 
compression gave origin to mountain-folding. The rock-masses 
in seeking relief from the crust-strains were pressed upward, 
and might under certain circumstances pierce the surface as 
a finger might pass through a button-hole. This, in Elie de 
Beaumont's opinion, was the explanation of the fact that granite 
masses so often form the summits and ridges of mountain- 
chains, whose flanks consist of uplifted sedimentary rocks. 
The latter, he said, were covered towards the base of the 
mountain for the most part by gently-inclined or horizontal 
strata, which spread over the neighbouring plains. The 
inclined strata often strike sharply against the horizontal 
layers, any marked contrast in the position of the neighbour- 
ing series of deposits indicating that after the deposition 
of the uplifted strata, and before the deposition of the undis- 
turbed series, a convulsion of the earth's crust had taken 
place in that region and had culminated in the uplift of the 
mountain-chain. The exact geological period of the crust- 
paroxysm could be determined from a comparison of the ages 
of the inclined strata and the horizontal layers reposing upon 


According to Elie de Beaumont, the ages of the mountain- 
systems as a rule correspond with the limits of geological 
formations, and therefore also with the "revolutions" indi- 
cated by Cuvier in the development of organic creation. The 
mountain-systems might in his opinion be regarded as chrono- 
logical documents bearing witness to the paroxysmal stages in 
the physical history of the earth's crust. He then attempted 
to ascertain after this method the ages of the various 
mountain-systems in Europe, deriving his facts partly from 
his own observations, partly from literature. 

While engaged on this inquiry, Elie de Beaumont became 
greatly impressed with the parallelism of the strike in the 
several component elements of a mountain-system. He 
remembered a saying of Werner's, that mineral veins with 
parallel strike afford evidence of the simultaneous origin of 
the vein fissures, and he applied this principle to mountain- 
systems, endeavouring to prove in the most detailed manner 
that mountain-systems or ranges with parallel strike were of 
simultaneous origin. The spherical form of the earth made it, 
however, difficult to determine the parallelism of mountain- 
systems far remote from one another, since in such cases the 
same term of geographical orientation would be used to 
describe directions which were not by any means parallel. 
Elie de Beaumont met this difficulty by treating the mountain- 
systems as tangents of earth-circles and arguing from the 
parallelism of the tangents. He regarded as parallel all 
mountain-systems which crossed the meridian at a like angle. 

With the principle of parallelism, Elie de Beaumont left 
the sure ground of inductive reasoning and entered into 
speculative matter, which unfortunately he continued to discuss 
during the remainder of his life. In his description of the 
mountains of Europe, published in 1852, they are represented 
as tangents of twenty-one circles, and from the inclination of 
these circles to one another Elie de Beaumont deduced a 
general geometrical law of orientation for the mountains of the 
earth. He also constructed a "pentagonal net-work" of the 
fifteen largest circles which corresponded to the corners of a 
regular isogon in the centre of the earth, and made it the 
fundamental basis of his elaborate scheme of the earth's 
mountain-systems. But the famous " Reseau pentagonal " never 
received general recognition, although it was much discussed 
for a time by the personal adherents of Elie de Beaumont. 


Several geologists, for example Studer and Hoffmann, who 
agreed with De Beaumont's fundamental ideas of upheaval by 
volcanic force, and his stratigraphical method of determining 
the age of mountain-systems, discredited his views regarding 
the simultaneous upheaval of parallel mountain-chains, as well 
as his assumption of sudden paroxysmal uplifts. They 
showed that the Alps, the Harz mountains, and the Erz 
mountains had suffered from repeated crust-movements. 
Still others, Constant Prevost, Ami Boue, Conybeare, and 
Charles Lyell, were in openly avowed opposition to Elie de 
Beaumont's doctrines from the first. 

Professor Thurmann in Porrentruy made a series of valuable 
observations on mountain-making processes. This observer, 
who devoted his life to the study of the Swiss Jura mountains, 
elucidated their structure and composition with masterly skill 
and breadth of conception. The arched forms, so conspicuous 
a feature of the Jura Chain, were explained by Thurmann as 
crust-uplifts due to vertically-acting subterranean forces, and 
he quoted several examples to show how these forces may 
sometimes raise portions of the crust, and sometimes give 
origin to faults along which the uplifted chains are disjointed, 
and the several portions move apart. 

Thurmann called the unbroken uplifted chains "arches," 
and distinguished as " combes " the crust-inthrows faulted into 
the middle of the arches ; a " combe " wholly surrounded by 
faults was termed by Thurmann a " cirque." While he used 
the term "fold" for the crust-arches themselves, he applied 
that of "val" for the syncline-or trough between neighbouring 
arches. He also gave distinctive names to mountain-valleys 
the longitudinal deep ravines at the outer flanks of the chains 
he termed "ruzs," and the transverse valleys cutting through 
several chains "cluses." 

The earlier treatises of Thurmann in 1830 and 1836 discuss 
the orographical features chiefly in relation to the original 
fold-forms of the Jura system and to general principles of 
mountain-folding and structures. His complete tectonical 
results regarding the causes and phenomena of relative crust- 
displacements were not published until 1856, a year after his 
death, at the age of fifty-one, from cholera. In these later 
papers Thurmann recognised the existence of one hundred 
and sixty incipient chains in the Jura mountains, only thirty 
of which could be regarded as of primary importance. He 


said they were separated from one another by somewhat 
crooked fault-lines which ran in approximately parallel 
directions, or diverged at various angles of bifurcation from a 
main chain. In the case of the principal chains, the highest 
fault-blocks were those on the western side of fault-lines, and 
the mountain-curves were convex towards the west. Speaking 
generally, Thurmann distinguished in the Jura mountains a 
zone of the highest chains, a central zone of uplift, and a 
slightly-folded plateau zone. From the whole structure of the 
Jura, he finally concluded, in opposition to his earlier views, 
that the chains had not taken origin as vertical uplifts, but 
that lateral forces had acted from the Swiss side and had 
compressed the strata along parallel folds. 

One of Thurmann's chief tenets was the long continuation 
of the plastic state in sedimentary deposits. He held that 
sediments remained plastic long after their deposition and 
during the processes of mountain-formation, and he therefore 
differentiated sharply between faulting, bending, crushing, 
and shearing movements effected while the sediments were 
still fairly plastic, and movements of adjustment accomplished 
after the mountains had been formed. He contested the 
hypothesis that rock already consolidated was reduced to a 
molten or plastic condition by the processes of mountain- 

While Elie de Beaumont and Thurmann were building up 
their theories of mountain-upheaval upon field observations, 
the English physicist, Hopkins, was trying to solve the 
problem upon theoretical grounds, and one of his doctrines 
is specially worthy of note. From his consideration of the 
pressures exerted by explosive gases, vapours, and other 
subterranean forces upon the crust, he concluded that in 
almost all cases of crust-fracture two systems of faults must 
take origin at right angles to each other, and must then be 
fundamental directive lines during the formation of continents 
and mountain-systems. 

Constant Prevost, in his report on the Island Julia 
(ante, p. 264), contested the theory of Elevation-Craters, and 
in opposition to Elie de Beaumont regarded the origin of 
mountain-systems and continents only as results of slow 
sagging of the crust, or of occasional inthrows when one side 
of the fissure was pressed outward and the rock-material was 
stemmed against it. Much later, similar ideas were enter- 


tained by Professor Charles Lory, by Ebray and Magnan. 
Professor Favre also dissented from the supposed vertical 
uplift of the Alps. In 1867, in a now classic description of 
the geology of Mount Blanc, he ascribed the complex fan- 
shaped arrangement of the rocks in that mountain to the 
action of strong lateral pressure. 

Important additions to the knowledge of mountain-struc- 
ture were meantime being made by the North American 
Geological Survey. In 1842, at a Congress of British and 
American Scientists, H. D. Rogers had expressed his views on 
the stratigraphical composition, the tectonical relations, and the 
mode of origin of the Appalachian mountains. The one-sided 
asymmetric arrangement of the folds in the Alleghanies, the 
absence of any central axis consisting of crystalline eruptive 
rocks, the fact that the whole mountain-system was composed 
of numerous parallel folds, most of them curved in form, 
could not in Rogers's opinion be brought into harmony 
with the theories of mountain-upheaval which were at that 
time current in Europe. He argued against the conception 
that ascending eruptive masses uplifted superincumbent rock- 
strata, and also against Prevost's opinion that mountains were 
formed as a consequence of local inthrows and crust 
subsidences. His own theory of mountain-folding supposed 
the disturbing cause to be wave-like pulsations into which the 
molten magma of the nuclear body was thrown from time to 
time, when the accumulated tensions in the earth's thin crust 
caused an actual rupture. The form, arrangement, and 
inclination of the folded strata were ascribed to a combined 
wave-like and tangential movement, which was also accom- 
panied by an injection of eruptive masses into the cavities 
created within the folds during the movement. 

Professor Dana 1 was the geologist who first gave clear ex- 

1 James Dwight Dana, born on the I2th February 1813 at Utica in 
New York State, entered Yale University in 1833 and made a journey to 
Europe during his college course. In 1838 he was selected as geologist 
and mineralogist for the Wilkes Exploring Expedition, and during the 
four years' voyage became acquainted with the coasts of South America 
and the Pacific Ocean. Dana was shipwrecked off the coast of Oregon, 
but fortunately succeeded in reaching San Francisco and sailed once more 
by the Sandwich Isles, Singapore, and St. Helena to New York. 
Thirteen years were then devoted to the examination and description of 
his geological and zoological collections. His reports on the geology of 
the Pacific Ocean, the volcanoes of the Sandwich Islands and coral reefs, 


From a Photo by Walker & Cockerell, London, E.C., of a Painting 
by S. Pearce. 


pression to the theory of horizontal compression in explanation 
of the origin of mountains. The early papers by Dana upon 
crust-movements were published in the American Journal of 
Science in the years 1846 and 1847. In them Dana boldly 
contested the possibility of continents and mountains being 
raised by the expansive force of subterranean vapours and the 
ascent of rock-magma; and he also dissented from the 
gravitation theory of his compatriot, James Hall (1859), 
according to which the gradual accumulation of sedimentary 
masses in areas of subsidence must, on account of the altered 
equilibrium, give rise to folding and fracture of the crust, and 
consequently to mountain-chains. Hall's idea was to a great 

j extent a modification of previous suggestions by Babbage and 
Herschel, but these investigators had attributed the subse- 
quent uplift of thick deposits in areas of subsidence to the 
expansion of the sediments on account of the high temperature 
in their deeper horizons. 

In common with Descartes, De la Beche, Cordier, Elie de 
Beaumont, and others, Dana considered the fundamental 
cause of crust - deformation to be the slow cooling and 
contraction of the earth's nucleus. But he made a closer 

I geological investigation than any previous observer of the 
precise mode of action displayed by the contracting 

! forces. 

Dana assumed that the orographical limits of continents 
and mountain-chains were determined by certain pre-existing 

| lines of minimum resistance (cleavage-lines) associated with 

I inequalities of thickness and temperature in the earth's crust. 

I He then argued that as the primitive earth cooled, the first 
crust-blocks that consolidated formed continents, and the 
pressure caused by shrinkage was most intense at the 
continental margins. There the greatest mountain-systems 
developed, and as a rule the height of a marginal mountain 

as well as his comprehensive works on Zoophytes and Crustaceans, are 
amongst the finest productions in the literature of scientific travel. Dana 
1 was a Professor at Yale University from 185010 1894, and died on the I4th 
April 1895. He was distinguished as a zoologist, geologist, and mineral- 
ogist ; his high merits were recognised in England by the award of the 
Wollaston and Copley medals. His Text-book of Geology, published in 
1863, has since passed through several editions, and has had a marked 
influence on geological thought and progress. Over a hundred papers 
by Dana have appeared in the American Journal of Science, and they 
treat almost every subject of general geological interest. 



range corresponded to the depth of a crust-hollow on the 
neighbouring portion of the ocean-floor. 

This preliminary hypothesis is clearly open to question, 
but a more important feature is Dana's assumption that the 
centripetal movement of the crust, as it endeavours to shrink 
along with the nucleus, is transmuted into tangential tension 
comparable with the strains that would be set up in the case 
of a falling arch. In Dana's opinion the horizontal pressure 
components thus originated fold the crust into arched ridges 
and trough-like hollows. Dana called the latter geo-synclinals, 
the former ge-anticlinals ; and he applied the qualifying term 
"monogenetic" to mountain-systems which owe their origin 
to a single arch or ge-anticlinal such as the Uinta mountains 
of Wyoming and Utah. On account of their frequent cracks 
and fissures, monogenetic crests are rapidly lowered by the 
action of subaerial denudation. 

The mountain-systems composed of several chains always 
arise, according to Dana, within geo-synclinals where immense 
masses of sediment have collected. As the older rock-horizons 
become mantled by ever-increasing thicknesses of sediment 
above, and the subsidence continues, the deeper strata are 
weakened by heat and pressure and readily tear asunder. 
The broken fragments yield to the horizontal pressures, are 
crushed into a narrower space against the lines of tearing, 
are folded and thereby uplifted. Dana called a mountain- 
system elevated from a synclinal area of subsidence a 
" synclinorium." The deeper geo-synciinals of past geological 
epochs have been as a rule next the continents, and the new 
mountains originated there slowly, the movements occupying 
vast geological ages ; after their emergence they were incor- 
porated with the main continental masses. 

Dana then discussed the conditions under which volcanic 
rocks might take a dominant part in the building up of 
mountain-chains. The earth's crust, he said, grew thicker 
by the continued progress of cooling, and the rocks became 
more and more resistant owing to the mechanical and 
chemical metamorphoses which they experienced in the crust. 
The process of mountain-making was consequently made more 
and more difficult in the older areas of disturbance, but as 
the tangential strain never relaxed, it might effect an upward 
pressure of the crust, culminating in rupture, and allowing 
the escape of volcanic rock at the surface. Hence the 


youngest mountain-chains were pre-eminent for the large 
I participation of volcanic rock in their composition, more 
especially along marginal fault-lines. 

Dana's views on mountain-building were based chiefly on 
the Appalachian Rocky Mountains, and were well adapted to 
the geological relations in North America. They were 
therefore widely accepted in that country. Many of the ideas 
were criticised by his compatriots, and the healthy interest 
awakened in the subject reacted favourably upon Dana's 
concept, as it enabled the author to revise and improve certain 
portions. Joseph le Conte was the most brilliant of Dana's 
; helpers in working out the evidences of horizontal components 
of pressure in mountain-folding; Dana so frequently cited Le 
Conte in his later publications that it is difficult to define the 
individual merits of the two geologists. 

To the North American geologists undoubtedly belongs 
the credit of founding the theory of horizontally-acting forces 
and rock-folding upon an ample basis of observation. 

Shaler distinguished between the uprise of continents and 
that of mountain-systems. Both were explicable upon the basis 
of the earth's contraction; but whereas the continents had taken 
origin from furrows which affected the whole thickness of the 
earth's crust, the mountains only represent foldings in the 
external parts of the crust which have served to relieve the 
lateral pressures produced by the contraction of the deeper 

The method of research followed by Professor Suess marks 
the beginning of a new epoch in the questions of crust- 
deformation. Two aspects appealed strongly to Professor 
Suess, the tectonical problems presented by individual 
mountain-chains, and the relation of all the mountain-systems 
on the surface of the earth to the physical changes in progress 
since the beginning of the earth's history. Since Elie de 
Beaumont's misguided effort, no geologist had attacked the 
question from its universal aspect, and the supreme scientific 
success attained by the first volume of Das Antlitz der Erde, or 
The Face of the Earth, by Professor Suess, was a tribute to a 
work accomplished with the highest bibliographical skill and 
literary finish, the fullest geological and geographical 
knowledge, a convincing array of scientific facts that never 
fail to suggest an endless reserve in the background, and 
above all a calm, judicial, elevated tone of inquiry which the 


end of the nineteenth century may well feel proud to have 
witnessed, and carried with it into its boasted wealth of 
scientific enlightenment. 

His earlier geological papers on special areas show Professor 
Suess only as the ardent field-surveyor, the lover of mountains, 
the laborious student compiling results from his own note- 
books. But the little book entitled Die Entstehung der 
Alpen^ or The Origin of the Alps, which was published in 
1875, already betrayed the dawn of new thoughts, full of 
freshness and interest. Professor Suess in that work contested 
the upheaval of mountains and continents by forces acting 
vertically upward ; he refuted the active participation of erup- 
tive rocks in the origin of mountain-chains, and after a brilliant 
description of the most important mountain-systems of the 
earth, he demonstrated that any arrangement of those accord- 
ing to geometrical laws was altogether illusory. The difficult 
problems of crust-displacements were, he said, so intimately 
associated with the question of the age and origin of 
mountains that the latter could not possibly be solved by 
any mathematical deduction or general rule obtained from 
leading-lines of strike and distribution, but demanded an 
accurate knowledge of tectonical structure in each case. 

A more detailed examination of the Alpine system 1 led 
Suess to the conclusion that the structure of this mountain- 
system was not symmetrical, as had previously been supposed, 
but was, on the contrary, essentially one-sided. The steep 
descent of the western Alps towards the plains of Piedmont 
and Lombardy indicated a curved fault-line, and the Alpine 
rocks had been folded together under the influence of a 
tangential force acting in north-west, north, and north-east 
directions from the leading crust-rupture. It had been cus- 
tomary to regard the zones of rock-formations on the south 
side of the eastern Alps as folded masses that had been 
pushed aside during the upheaval of the central chain, but 
Suess contested this, saying these zones represented an 
independent chain which had been pressed against the 
Alps by a horizontal force acting towards the north-west. 
He pointed out that farther east still another chain, the 

1 This name was applied, by Suess in wider sense to include the Alps 
proper, the folded Jura mountains, the Carpathians, the Hungarian moun- 
tains, the Dinaric ranges along the eastern shores of the Adriatic Sea, and 
the Apennines. 


Hungarian mountains, was introduced between the central 
Alps and the southern zones. Professor Suess then demon- 
strated a similar unilateral structure for the Balkan, Caucasus, 
and Ararat mountains, and in all cases ^ the action of the 
tangential forces had been from south to north. 

Hence a surprising similarity was demonstrated between the 
mountains of Europe and those in North America which had 
been described by Rogers and Dana, and the theory of 
lateral compression so widely accepted by American geologists 
seemed applicable to European mountain-chains with but few 
modifications. Elie de Beaumont's method of determining 
the ages of the mountain-chains was clearly unsuitable 
upon this new conception of their structure. According to 
Professor Suess, the tectonical disturbances which gave form to 
the present Alpine system had begun in the Mesozoic period, 
and had continued not only to the close of the Miocene time, but 
(at least on the southern slopes) into the Pliocene and possibly 
even the Diluvial Age. In considering the actual lines of 
deformation, Suess pointed out that allowance must be made 
for the retaining influences exerted by neighbouring immovable 
mountain-blocks, by ancient intruded and interbedded volcanic 
rocks, and by the resistance of the rock-folds themselves. 

A study of the older mountain-masses (afterwards called 
" Horsts" by Suess) limiting the Alps on the west and north, 
showed that the same direction of force which had folded the 
Alps had also determined the structure of the Riesen moun- 
tains, the Sudeten mountains, the Bohemian forest, the Harz, 
the Ardennes, etc., and that this Central European mountain- 
system of high geological antiquity had, like the later Alpine 
system, been compressed by horizontal forces acting towards 
the north-west, north, or north-east. Although in Europe as 
in North America, the dominating direction of pressure had 
come from the south, there were also evidences of compres- 
sion towards the south. Val Sugana in the southern Alps, 
Istria, Dalmatia and the Karst, the Ifer mountains, and 
the Teutoburg forest were mentioned as types of southward 
compression. Yet so prevalent was the northern direction 
of movement over vast regions between the Caspian Sea and 
the American shores of the Pacific Ocean, that one might 
feel tempted to deduce a general streaming of rock-material 
towards the North Pole throughout the whole Northern 
Hemisphere. But several facts contradicted such a con- 


elusion. On the eastern boundary of the aforesaid region a 
number of disturbances were apparent, which were frequently 
associated with volcanic phenomena, and had caused the 
tremendous north-south fault of the Red Sea and the 
Jordan valley, also influencing the direction of strike of 
the Ural mountains and the western Ghats. East of this 
transversal line of disturbance, the leading Asiatic mountains 
had not in Europe the convex side of the strike-curves towards 
the north, but the convexities were towards the south. 

A comparison of the Himalayas with the Alps showed a 
remarkable agreement between the two distant mountain- 
systems; Mesozoic, Palaeozoic, and Crystalline rocks com- 
posed the high mountain-lands of both systems, yet there 
was the fundamental difference that the Tertiary rocks 
in the southern foreground of the Himalayas corre- 
sponded with those in the northern Molasse Zone of the 
Alps. Medlicott had already concluded from the general 
structure of the Himalayas that the chain had taken origin 
as the result of lateral compression from the north, and Suess 
tried to demonstrate a similar direction of movement, to the 
south or south-east, in other systems of Central Asia. 

Suess agreed with Dana's opinion that the sedimentary rocks 
of the Euro-Asiatic systems had accumulated in pelagic geo- 
synclinals; and he brought the frequent gaps and uncon- 
formities in the succession of strata carefully into relation with 
former oscillations in the extent of the ocean. Suess described 
in greater detail the transgression of the Cenomanian Ocean 
which spread over a considerable part of Europe, North and 
South America, and northern Africa, and drew from it the 
conclusion that stratigraphical evidences of transgressions 
and withdrawals of the waters of the ocean were even more 
valuable as a means of determining the approximate eras of 
certain events in the Earth's history than the discovery of the 
relative ages of mountain-systems. 

In the concluding chapter of this work on the origin of the 
Alps, Professor Suess summarised his results as follows : 
the strikes of mountain-chains do not always run parallel with 
the greater circles of the earth, but may be diverted by various 
obstacles; the major fold-systems of mountains take origin 
frequently, if not exclusively, in geo-synclinals and demand 
enormous periods for their development. Volcanoes play a 
subordinate part in the formation of mountains. Most 


mountain-systems have unilateral structure, and there has 
been in North America, Europe, and North Africa a general 
movement of rock-masses towards the north, in Asia towards 
the south. 

Suess then enunciated certain principles of mountain- 
building. The simplest type of a mountain-system is that 
which begins with the occurrence of a rupture or fault rec- 
tangular to the direction of contraction, the severed crust-block 
then moving onward in the direction of the contraction (ex- 
ample, Erz mountains). The second and most frequent type 
is that which begins with the disposition of a principal fold 
striking transversely across the contraction and inclined in the 
direction of the contraction, a fissure then forming in the fold 
at the line of maximum tension. The front part of the fold 
moves in the direction of the contraction and pushes the 
sedimentary rocks before it into further foldings, the other 
part of the fold sinks, and volcanic rocks escape at the line 
of fragmentation and subsidence (example, Apennines and 
Carpathians). In a third type of mountain-building, several 
parallel folds arise, occupying a greater surface breadth, and 
usually ending on the inner side of the innermost fold with 
a steep crust-fracture (example, folded Jura mountains, 
Ardennes, Taunus, Appalachians). It depends on the inten- 
sity and direction of the folding- force, on the nature of the 
resistance, and on the greater or smaller brittleness of the 
varieties of rock, whether the secondary folds are preserved 
or if they are deformed and pass into faults whose planes are 
inclined inward to the mountains and serve as planes of 
overthrusting. In extensive regions the contracting force 
seems to have had the same direction during successive geo- 
logical epochs. 

Suess agreed with Shaler that the continents represent 
contractions of the whole earth's crust, whereas the mountain- 
systems are to be regarded merely as foldings of the more 
superficial layers of the crust. In addition to the folded 
mountainous portions of the earth's crust, Suess emphasised 
the presence of resisting crust-areas which, like Bohemia, are 
composed of old mountain-masses piled against or across one 
another like pack-ice, or like the vast Russian block consist of 
undisturbed horizontal strata. Such unyielding areas of the 
crust are frequently characterised by considerable gaps in the 
sedimentary series. Their geographical distribution decides the 


form and the course of the folds into which the intervening 
more yielding portions of the earth's surface have been thrown 
by the tangential strains of contraction. While the first cause 
of mountain-making is the secular cooling of the crust, the 
precise form of a mountain-chain is subject to the modifying 
conditions introduced by these ancient and resistant crust- 
blocks or "archiboles." 

The above are some of the leading conceptions in the 
remarkable work on mountain-structure published by Suess 
in 1875, a d its great influence may be judged from the flood 
of literature upon this subject which has poured forth since 
that year. It is impossible to refer here to more than the 
most important of these publications. 

After a long series of researches in a complicated district of 
Switzerland, Professor Heim, in Zurich, published in 1878 
his famous work, Untersuchungen iiber den Mechanismus der 
Gebirgsbildung. The two geological maps and fifteen illus- 
trative plates accompanying the text were lithographed by the 
author himself. The scientific insight and technical skill 
possessed by Professor Heim form a rare combination, and 
have brought his views on mountain-structure wide popularity 
and acceptance. 

Heim concentrated his attention on the tectonical pheno- 
mena of folding. He depicted in the "Glarus Double- Fold " 
an appearance which seemed contradictory to any doctrine of 
mountain-movement, since on the north side of the central 
Alps, where, according either to the conception of symmetry or 
asymmetry of the chain the folds should have been towards 
the north, Heim's observations showed that the major folds on 
the north and south of the Glarus area had been overthrown 
towards one another, and the upper portions had continued to 
travel as "thrust-masses" advancing from opposite directions 
towards one another. This was clearly inexplicable on the 
assumption of a uniform direction of the horizontal movement 
of the crust, and Heim concluded that the inclination of over- 
cast folds depended upon local inequalities of resistance, upon 
the presence of older folds as well as upon the relative height 
of the two bases of origin on the opposite sides of any individual 
fold. The second volume of Heim's work treats the general 
problem of Mountain Architecture. Using his own field 
observations as the ground-work of his discussion, he describes 
the phenomena of rock-deformation during crust-movement 


under several headings : curvature, plication, crush, shear, 
cleavage, distortion of rock-material and of fossils. He 
opposes Thurmann's idea that the rocks are primarily 
plastic and remain so during the mountain-movements, and 
assumes that the rocks of our mountain-chains have been first 
consolidated and afterwards altered during the crust-movements; 
the alteration might be accompanied by fissures and faults or 
might take place without any fracture, both modes of trans- 
formation being quite independent of the physical and chemical 
constitution of the rocks. Alteration without fracture only 
occurred at great depths, and was most frequent in the older 
rocks. According to Heim, the essential conditions for such 
alteration are the presence of a heavy superincumbent load of 
rock, and the action of pressures from all sides upon the rock- 
particles, so that even the most brittle mass of rock would 
be converted into a state of latent plasticity. The work done 
by horizontal pressures is the great truth which Professor Heim 
seeks to inculcate. He brings forward numerous observations 
to prove the passive behaviour of the "Central Massives" during 
the upheaval of the present Alpine system. In opposition to 
Studer's idea that the massives had represented active local 
centres of disturbance, Heim points out that the crystalline 
rocks present in these areas themselves show deformation and 
alteration explicable only upon the assumption that they had 
suffered no less than the rocks in the northern and southern 
zones of the Alps from a system of horizontal pressures common 
to the whole Alps. In Professor Heim's opinion, the individual 
forms of the Central Massives as lenticular or fan-shaped arches 
or simple domes had been determined by modifying local in- 
fluences during the epochs of Alpine upheaval, but had no 
connection with volcanic subterranean forces. On the con- 
trary there is, according to Heim, no field evidence whatsoever 
that the igneous rocks of the Central Massives exerted forces 
of compression upon the sedimentary strata in contact with 

Heim therefore agrees with the general results of Suess, 
and explains mountain-making as a consequence of nuclear 
contraction, crust-subsidence, and the complex action of 
horizontal strains through the layers of the crust. He 
calculates that the plication of the Alps has reduced the 
breadth of that portion of the crust by a distance of about 
seventy -four miles; hence the crust contraction would seem 


to be a very appreciable amount in the case of the greater 
mountain-systems. On the other hand, Heim calculates that 
the earth's diameter has not been shortened even one per cent, 
by the processes of subsidence and mountain-folding. With 
regard to the age of the Alps, Heim concludes that the central 
chains are older than the outer, that the strains have wholly 
ceased in the inner portions of the Alps, but continued along 
the northern chains into the youngest Tertiary periods, and are 
possibly even now in progress. 

According to Heim's theory of latent plasticity, the rocks 
at a depth of nearly 7000 feet would be in a condition that 
would preclude the possibility of gaping fissures. This 
assumption is correlated with the characteristic feature in 
Heim's geological surveys, namely, the pre-eminence of folds 
in all possible forms, and the subordinate place assigned to 
faults. These have proved somewhat vulnerable points of 
attack in an otherwise classic work, and have been called in 
question by many eminent geologists during the twenty and 
more years that have elapsed since the publication of the 

Giimbel, Broegger, Stapff, Pfaff, Rothpletz, and others have 
opposed the theory of plasticity upon various grounds. All 
experimental attempts to reduce rocks by mere compression 
only caused fragmentation of the material. Pfaff found that 
many rocks might be subjected to a pressure of more than 
20,000 atmospheres without showing any tendency to become 
plastic. Moreover, it is not in accordance with the known 
phenomena of volcanoes and earthquakes to assume that 
crust-fissures cease at comparatively small depths. 

The experiments of M. Daubree and M. Favre are 
especially noteworthy. Daubree started from the standpoint 
that not only horizontal, but also vertical components of 
force have acted in bending and folding the rocks of the crust. 
His apparatus consisted of a rectangular iron frame, to contain 
the material under pressure. The pressure was applied from 
the side, but sometimes simultaneously from above. Instead 
of the alternating layers of wool, cotton, and clay which had 
been used in the experiments of Sir James Hall in Edinburgh, 
Daubree arranged different kinds of metal plates and sheets 
of wax mixed with clay, resin, or turpentine. By varying the 
conditions of his experiments in respect of the intensity and 
direction of pressure, and the kinds of material, M. Daubree 


obtained types of folding and deformation which coincided 
with many of those represented in nature. The first account 
of Daubree's results appeared in 1878, and in the same year 
Professor Favre of Geneva published his illustrations of clay 
strata which had been placed upon a stretched band of 
caoutchouc, and thrown into folds on the contraction of the 
elastic basis. In 1888, Mr. Cadell carried out a series of 
pressure experiments and attained excellent imitations of the 
tectonical disturbances in mountain-systems. An attractive 
experimental elucidation of the Appalachian mountains was 
given by Mr. Bailey Willis in his work entitled The Mechanics 
of Appalachian Structure. 

All those experimentalists have demonstrated that under 
strong lateral pressure the material is not only plicated but is 
fissured and faulted in many different ways, and geologists 
generally are inclined to think that Professor Heim has not 
allowed sufficiently for the complicating effects of crust- 

The geological significance of fissures and faults was fully 
realised by the Wernerian School; this was only to be 
expected, since the foundation of Werner's doctrines was 
his intimate knowledge of the vein-rock that occurred in the 
crevices and fissures of the crust, and his careful observation 
of the relative displacements of the rock on the opposite sides 
of fault-fissures. From time to time special works on faults 
have appeared in mining literature. One of the best known 
earlier works is Carnall's description of the fissures in the 
Carboniferous district of Silesia, published in 1836; numerous 
special papers on the British mining districts are included in 
the Reports of the Geological Survey; and Kohler in 1886 
published a valuable monograph, entitled Die Storungen der 
G tinge, Flotze und Lager. 

The faults in mountain-regions were examined by De la 
Beche, Sedgwick, Thurmann, Harkness, and many others, and 
their origin commonly ascribed to contraction and mechanical 
strain; William King explained them as due to processes of 
crystallisation. The mechanical strains in the crust during 
mountain-making are undoubtedly the most important factor, 
and Professor Daubree imitated the effects of strain in a series 
of experiments. He subjected plates of glass, pieces of rock, 
and wax prisms to torsion and to vertical and lateral pressures, 
and produced fissures and displacements which could bear 


detailed comparison with the phenomena of crust-fracture 
in nature. Daubree also elucidated the influence of such 
fractures on the subsequent surface conformation of the earth, 
and especially on valley erosion. 

Reyer in his Theoretische Geologic, published in 1888, 
discusses the causes and phenomena of crust-ruptures. He 
refers fractures to differences of tension arising from various 
causes, inequality of the superincumbent weight or in the 
rate of gain and loss by chemical changes, and inequality in 
the access or abstraction of heat in the rocks of adjacent 
areas. Dr. Reyer cites numerous examples of step-faults, 
trough-faults, and fault-nets, in order to show that areas of 
subsidence bounded by fault-fissures are frequently strength- 
ened by the injection of eruptive masses, and are rendered 
so much the more resistant in subsequent crust-disturbances. 

The first volume of Suess's Antlitz der Erde appeared in parts 
during the years 1883-85 ; the second volume followed in 1888; 
and the third and last volume has recently been completed. 
The author incorporates in this work many ideas which he 
had enunciated in skeleton in the Entstehung der Alpen. 
But the later work is not limited to the consideration of the 
origin of mountains and continents, it .surveys the whole 
history of terrestrial change in the course of the geological 
epochs. In the hands of the most accomplished of foreign 
geologists, and one of the strictest logicians of any age, crust- 
tectonics may be almost said to have been elevated into a 
new inductive philosophy of earth-configuration. 

The leading purpose of the work is to explain the present 
conformation of the earth's surface upon the basis of the 
previous changes in the oceans and continents of the earth. 
And first the movements in the solid outer framework of the 
earth are considered. 

Suess begins by discussing the Deluge of the Scriptures, 
as one of the last grand geological events, which visited 
Mesopotamia with a devastating inundation, probably the result 
of an earthquake or a cyclone from the Persian Sea. In 
addition to the Mosaic account, the Izdubar Epic of the 
Babylonian Berosus serves as the historical basis of this 

A second chapter treats of Earthquakes, and a third 
elucidates the various kinds of dislocations associated with the 
contraction of the earth's nucleus. The movements are 


resolved into tangential and radial tensions, which give effect 
to horizontal and vertical displacements. Under horizontal 
displacements Suess describes folds, anticlinal domes, over- 
thrusts, and lateral shifts effected by dip-faults. The vertical 
displacements are evidenced by subsidence or inthrows, and 
they are accompanied by numerous fissures and faults, which 
may again be sub-divided into peripheral, radial, diagonal, and 
transversal faults. The nature of the subsidence in dislocated 
segments of the earth's crust determines the arrangement of 
the faults as limiting-lines of crust-basins, crust-troughs, 
flexures, or table-lands. The combination of a subsiding 
and tangential movement gives origin to specially complicated 
tectonical appearances, such as the development of fore-folds 
and back-folds. 

Suess regards volcanoes only as slight and superficial 
indications of important phenomena in the nuclear mass of 
the earth. He describes a number of examples showing the 
gradual denudation and partial disturbance of volcanoes, and 
establishes a " series of denudation forms " intended to prove 
that there is no fundamental difference between the volcanic 
explosions and ejections of the present time, the massive flows 
of earlier periods, and the laccolites and deep intrusions of the 
oldest periods. The fissures and dykes of active and extinct 
volcanoes are carefully discussed, also the dislocations caused 
by earthquakes. 

After these preliminary chapters, Suess makes a compara- 
tive investigation of the mountain-systems of the earth, and an 
attempt to discover their geological history from their tec- 
tonical structure. To the geologist the subject is opened out 
with unflagging interest. Beginning with the Northern Sub- 
Alpine area, Suess emphasises the obstructive influence which 
had been exerted by the mountain-ranges of Central Europe, 
the Sudeten mountains, and the Russian plateau. These 
resisting crust-blocks had for the most part successfully 
stemmed back the advancing Alpine folds, or in the case of 
the Sudeten and a part of the Russian plateau, the northward 
crust-creep had carried the Carpathian folds partially over the 
ancient mountain-masses. 

Suess elucidates the direction of strike of the dominant 
folds in the Alpine system, and his description of the cur- 
vature and whirl-shaped arrangement of the leading lines 
of strike has thrown an entirely new light upon Alpine geology. 


The older view, that in the Northern Hemisphere, from the 
Caspian Sea to the American shores of the Pacific, folding- 
movements had been directed to the north, north-west, or 
north-east, is shown to be erroneous for the southern Apen- 
nines and other outrunners of the Alpine system, as well as 
for the coastal chains in North America. A special chapter is 
devoted to the work of Mojsisovics on the inthrown area of 
the "Dolomites" in South Tyrol, with which the origin of the 
Adriatic Sea is associated. 

Another chapter is devoted to the geological history of the 
Mediterranean Sea, which he proves to be a remnant from a 
much greater ocean. He calls this ancient ocean "Thetys," 
and by an exhaustive discussion of the various Tertiary 
deposits demonstrates the former extent, boundaries, and 
phases of development of the original ocean of "Thetys." 
It extended across the Atlantic Ocean to the southern coasts 
of North America, and through Central Europe to the inner 
recesses of Central Asia. The fragmentation of the neighbour- 
ing continents, the recent inthrows of the y^Egean and Black 
Seas, are described with admirable mastery of detail. 

The following chapters treat the Sahara table-land, with 
its continuation towards Arabia and Palestine ; the broad 
South African table-land, which formerly extended as 
" Gondwana Land " across Madagascar to Southern India and 
Australia and is bounded on all sides by a faulted coast ; and 
lastly, the mountain-systems of India and Central Asia and 
their tectonical relations to the Alps and European mountains. 
Suess then proceeds to describe the leading features of America. 
In South America there is a certain unity of structure. In 
the east and in the middle the great Brazilian table-land is 
composed of little disturbed Palaeozoic strata ; in the west the 
folded mountain-chains are mostly composed of Jurassic rocks. 
Still younger strata occur near the Pacific coast, and the 
volcanoes and earthquakes of this area indicate the continuance 
of crust-disturbances in the present day. 

Central America is interposed between North and South 
America with a structure geologically independent of either, 
and representing a part of the former land-girdle of the Thetys. 
In North America, the Appalachians, the Mountains of the 
West, and the intervening table-lands afford the author 
frequent opportunity of discussing the American literature on 
the origin of mountain-systems. 


The first volume concludes with a summary of the most 
important results obtained throughout the work.' It is 
pointed out that the names Old and New World are, geo- 
logically speaking, quite unjustified, as the greater part of 
North America has been exposed as dry land since the 
Cretaceous epoch, and is therefore of considerable antiquity. 
South America has its own distinct structure ; it may be 
described as a gigantic crust-buckle bounded on three sides 
by high mountain-walls, but unbroken by any tectonical lines 
towards the east and north-east. 

In the Old World three dissimilar regions have been welded 
together: (i) the southern parts of the ancient Gondwana 
Land, which has never been completely submerged since the 
conclusion of the Carboniferous epoch ; (2) Indo-Africa, the 
present Sahara, Egypt, Syria, and Arabia, covered by the ocean 
in the Cretaceous epoch, but never subjected to folding-move- 
ments since Palaeozoic time ; and (3) Eurasia, the north-west 
of Africa, Europe, and the remainder of Asia. The southern 
borders of Eurasia are strongly folded, and throughout long 
tracts they have been thrust above the Indo-African table-land. 

The second volume begins with a historical account of the 
different opinions regarding secular movements of upheaval 
and depression of the land. Suess points out the advantages 
of the terms "positive" and "'negative" as signifying the 
relative character of coastal displacements (ante, p. 292). 

Two of the most brilliant chapters in the work are devoted 
to the boundaries of the Atlantic and Pacific Oceans. All the 
erudition of a century is summed up in these pages; as one 
reads, broad geological portraits of the face of the earth as it is 
and as it was are called forth, till one forgets to marvel at the 
magician's touch or question the individual features. A com- 
parison of the North European and North American fault-areas 
discloses unexpected homologies between the two territories. 
The re-construclion of the ancient Armorican and Variscan 
mountain-systems in Central Europe, the elucidation of their 
losses by fracture and denudation, and the proof of the 
similarity in the direction of the later folding that gave origin 
to the Alps and Pyrenees, are masterpieces of scientific 

The Face of 1he Earth is intended, however, not only to 
explain the origin of mountains, but also to trace in chrono- 
logical succession the chief vicissitudes of the solid crust since 


it began to form. A detailed account of the Palaeozoic, 
Mesozoic, and Tertiary oceans, with their transgressions and 
retrogressions, comprises many new conceptions, and leads the 
author finally to the consideration of the oscillations of the 
ocean surface at the present day. The emerging coasts of 
Scandinavia are viewed as proof of lowered sea-level, and the 
general opinion in favour of crust-elevation is strongly op- 
posed. Similarly, Suess explains the strand displacements in 
progress on the coasts of the Mediterranean Sea, the Pacific 
and Indian Oceans, as the result of movements in the aqueous 
envelope of the earth, but not in the solid crust. 

According to Suess, ruptures and collapses affecting the 
whole thickness of the earth's crust, together with tangential 
folding of the upper horizons, are the forces to which the earth 
originally owed its surface conformation. There is no such 
thing as an active or passive emergence of portions of the 
earth's crust; in the estimation of Suess, the theory of elevation 
is a great error. He thinks it impracticable to ascertain the 
ages of the mountain-systems by any such ingenious method 
of calculation as Elie de Beaumont attempted, seeing that as 
a rule the upheaval of a mountain-system occupied protracted 
intervals of time. Nevertheless, Suess is inclined to correlate 
the grand physical events of the earth's history with those of 
the development of the organic world, and thinks it possible 
in this way to erect a natural and universal classification of the 
formations. For this purpose it is not so much the origin of 
new mountain-systems that comes into question as the periodic 
recurrence of those great pelagic transgressions, whose cause of 
origin until now has not yet been discovered. 

Many of the hypotheses suggested by Suess will probably 
not endure the criticism of the future. Yet there can be no 
doubt that even the expression of a hypothesis having due 
respect to all known data marks an important step in advance. 
In the midst of the present activity in conducting detailed 
investigations there is a certain danger that scientific workers 
may become parochial in their interests and teaching ; but a 
work like that of Suess, so cosmopolitan in its standpoint, 
reminds all workers of their community of aim, rouses each 
one from the particular to the general, and brings him back 
with renewed vigour and mental insight to the particular. 
The time was ripe for an effort to establish systematic clearness 
in the acquired abundance of detail and to seek for compre- 


hensive laws and principles. One of the most distinguished of 
living geologists, Professor Marcel Bertrand, writes in the pre- 
face to the French translation of Suess's work, by M. de Margerie: 
''The creation of a science, like that of a world, demands more 
than a single day; but when our successors write the history 
of our science, I am convinced that they will say that the work 
of Suess marks the end of the first day, when there was light;' 

Suess has secured almost general recognition for the Con- 
traction Theory. Yet there are individual attempts to explain 
mountain-making in some other way. Amongst these the most 
worthy of note is Mellard Reade's attempt to work out the 
Huttonian expansion theory in detail and to make it agree 
with the ascertained facts of modern geology. Mellard Reade 
made a number of experiments on the expansion of metals and 
rocks under different modes of heating, and applied his results 
theoretically to explain the movements within the earth's crust. 

Like James Hall and Dana, Mellard Reade starts with the 
assumption that mountain-making takes place only in districts 
of thick sedimentary deposits, and that there is an increase of 
temperature in those parts of the earth's crust on account of 
the additional thickness, and therefore proportional with it. 
Whereas Babbage, Lyell, Dana, and others suppose that 
the force of expansion called forth by the increase of 
temperature acts only in linear directions, vertically upward, 
Mellard Reade shows that this force must tend to expand 
rocks cubically, i.e., upward, downward, and laterally. The 
lateral expansion of the rocks in the heated area is resisted 
by the relatively less heated rocks of adjacent areas, the com- 
pression of the expanding rocks causing them to fold and buckle. 
The upper layers being less influenced by the earth's heat than 
the lower are in a condition of greater tension, while the lower 
are more strongly compressed. Both are separated by a neutral 
zone, in which the rocks experience neither tension nor com- 
pression ; this zone is called the "level of no strain." 

The rocky floor upon which the thick mantle of deposit has 
gathered necessarily participates in the subsequent rise of crust- 
temperature, the expansion, and the compression. Therefore 
the sedimentary strata of high antiquity composing the floor 
are subjected anew to heat and pressure, are folded and 
crushed in the most varied manner, and in their plastic state, 
since they are stemmed back by the lateral resistance of cooler 
areas and harder masses of rock, they are readily pressed 



towards the lines of least resistance in the mountain-system, 
namely, the anticlinal axes of the folds and arches. Thus they 
accentuate the appearance of upheaval at the surface, and form 
the axes of the highest chains, which as a rule consist of ancient 
crystalline rocks. 

But as the origin of a mountain-system occupies long geo- 
logical epochs, many changes of temperature may take place 
in the subterranean masses. Every rise of temperature causes 
a new movement of expansion, and the mountain-chains may 
rise higher and higher above the surrounding areas. Fissures 
and faults are phenomena of contraction produced by cooling, 
and are therefore usually younger than the folding and upheaval 
of the mountain-chains. With every crust-rupture a subsidence 
of one or both sides of the fissure is commonly associated. 

Mellard Reade cites examples chiefly from British and North 
American geological literature in support of his theory. The 
weakness of the theory consists in its treatment of mountain- 
making as a merely local phenomenon ; it assumes rather than 
explains that the expansion of limited crust-blocks by little and 
little can effect the uprise of vast mountainous tracts. 

The American geologist, C. E. Button, in a paper " On 
some of the Greater Problems of Physical Geology," in 1892 
also contests the Contraction Theory and proposes his theory 
of " Isostasy." He points out that the earth's crust is not 
homogeneous, but consists of heavier and lighter masses ; the 
effort to arrive at equilibrium causes the heavier masses to 
subside and the lighter masses to rise as crust-buckles. If an 
area which has already subsided is weighted by thick masses 
of sediment it must sink farther, and if simultaneously the 
adjacent crust-buckle is lowered by the agencies of surface 
denudation, the socket of the arch is so much lightened and 
rises farther. Should these movements overcome the rigidity 
of the earth's crust, Button supposes that in the littoral sedi- 
ments, crust-creep or flow takes place towards the continent in 
course of denudation, and this flow movement may become 
so intense as to produce folds and build up mountain-chains. 

Br. Reyer, another opponent of the Contraction Theory, 
has suggested a theory of mountain-making based upon exten- 
sive crust-slip. He assumes that every system of crust-folds 
begins with a crust-rupture and with the sinking of several 
crust-blocks towards one direction, so that the earth's relief is 
made unsymmetrical, with a definite slope on one side. If 


the sedimentary rocks beside a rupture are tilted by upheaval, 
then, according to Reyer, the rock-strata glide downward and 
as they do so fall into complicated folds. 

An Alpine geologist of wide experience, Professor Rothpletz 
in Munich, holds the Contraction Theory to be inadequate as 
an explanation of volcanoes and of the unlike distribution 
of gravity in the earth's crust. He believes that a better 
explanation is afforded on the basis of crust-expansion in 
certain regions. 

Rothpletz recognises three distinct spherical zones of rock- 
material in the earth, according to their physical condition. 
Below the rigid crust is the viscous or molten nucleus, and 
between both a zone of cooling and consolidation. Professor 
Rothpletz assumes that the masses in the intermediate zone do 
not contract as they would on cooling under normal pressure of 
superincumbent rock, but expand as they cool, in analogy with 
bismuth and other substances. From this zone, therefore, 
vertical and tangential pressures are exerted upon the solid 
crust. At localities of weak resistance the crust is torn, the 
expansion of the intermediate zone pushes the crust upward 
and produces continents or table-lands at the surface, and the 
seams are invaded by the uprush of molten magma from the 
nucleus. At the same time the tangential tension in the 
emerged continents tries to relieve itself locally by the forma- 
tion of folds. Hence mountains are upheaved and volcanic 
invasions occur on the continents at the places of least 



THE investigation of the rocks which compose our earth's 
crust has always been conducted along two directions of study : 

(1) the investigation of the mineralogical and chemical 
composition, the structure of rocks, their mode of occurrence ; 

(2) the investigation of their mode of origin. 

The systematic arrangement and the morphology of rock- 
varieties has been constructed mainly upon a mineralogical 
basis ; the questions concerning the origin of rock-varieties 
have been handled more from the geological and chemical 
side. A distinction between massive eruptive rocks and 
stratified deposits \vas early recognised in petrographical 
literature. Mutton's was the genius which first differentiated 
clearly between plutonic, volcanic, and sedimentary rocks in 
point of origin ; while Werner, too biassed by Neptunistic 
doctrines to perceive the fundamental truths which Hutton 
had taught, nevertheless accomplished the task of erecting a 
systematic classification of rocks upon mineralogical con- 

During the first half of the nineteenth century, all petro- 
graphical works followed Werner's system. His determina- 
tion of rocks as simple or composite occurs in most of the later 
attempts at classification, and also his fundamental principle 
of differentiating the essential and the accessory minerals in 
mixed rocks has been continued to the present day. 

Brongniart had in 1813, in his table of Composite Rocks, 
assigned great importance to the structural relations, and dis- 
tinguished accordingly three chief classes : i, the " isomerites," 
or granitoid varieties of rock, in which the individual elements 
are united only by crystalline aggregation, and there is 
no finer matrix, e.g., granite, syenite, protogine ; 2, the 
"anisomerites," or porphyritic and hemicrystalline varieties, 



in which the chief mineral constituents lie imbedded in a 
"matrix'' or ground-mass, e.g., gneiss, schist, phyllite, porphyry, 
trachyte, obsidian, lava ; 3, the " aggregated " or fragmental 
varieties, which take origin by mechanical means, and whose 
ingredients are cemented together by subsequent infilling of 
material, e.g., psammites (sandstone, greywacke), pudding- 
stones, and breccias. 

Brongniart, as well as his predecessors Hauy and Cordier, 
confined themselves exclusively to the mineralogical com- 
position and structure of the rocks, without respect to their 
mode of occurrence, their age, or their origin. While this 
method of treatment proved undoubtedly beneficial to the 
development of systematic petrography, it endangered the 
connection between geology and petrography, and in this 
respect the direction initiated by the French petrographers 
must be regarded as retrograde in comparison with the 
Wernerian School. 

The best and most complete work of that time on petrology 
was Leonhard's 1 Charakteristik der Felsarten (1823-24). In 
this work likewise the mineralogical standpoint predominates, 
but the Wernerian influence is apparent in the frequent 
digressions which give information regarding the occurrence 
of the different kinds of rock in the field and their mode of 
origin. Leonhard distinguished four sub-divisions of rocks : 
T, rocks composed of unlike elements; 2, rocks apparently 
uniform ; 3, derivative or fragmental rocks ; 4, friable and in- 
coherent rocks. As all Leonhard's distinctions were founded 
on macroscopic examination of the rocks, the group of the 
"apparently uniform" rocks is quite artificial, and the limits 
of the others are unsatisfactory. 

Cordier 2 had suggested in 1815, according to the precedent 

1 Carl Casar von Leonhard, born 1779 at Rumpenheim near Hanau, 
studied in Marburg and Gottingen ; in 1800 entered into the Hessian 
Government Service; in 1810 was appointed Councillor of the Exchequer 
in Chur Hesse, and afterwards Director of Domains; in 1816 accepted a 
call to the Munich Academy, but left Munich in 1818 to be Professor of 
Mineralogy and Geognosy at the University of Heidelberg, where he died 
on the 23rd January 1862. 

2 Pierre Louis Antoine Cordier, born 1 777 i n Abbeville, began life as 
a mining engineer in 1797 ; took part under Dolomieu in the Egyptian 
Expedition ; in 1819, succeeded Faujas de Saint-Fond as Professor of 
Geology at the Botanical Garden, and at the Restoration of the Empire 
was made a peer of France. He died in 1862. 


of Fleuriau de Bellevue and Dolomieu, to pulverise the 
apparently homogeneous rock-varieties, to separate the particles 
by weight, and test them partly below the microscope, partly 
with the magnet, partly by chemical means ; but this manner 
of research proved far from successful, as it was extremely 
difficult to identify the minute mineral particles. It showed, 
however, that basalt was a composite rock. 

The Scottish geologist, Professor William Nicol, in 1827 
introduced a method of preparing thin sections of fossil 
woods to be examined by the microscope, and about the same 
time constructed a polarising microscope for the special 
investigation of crystals. The insight of this gifted man in 
petrographical pursuits, no less than in respect of the difficult 
problems of the geology of the Scottish Highlands, failed to 
carry conviction into the minds of his contemporaries. A 
few petrographers certainly adopted his method of examining 
fossil woods, and it was by this means that Goppert was 
enabled to detect the important constituents of coal. 

In the hands of Ehrenberg, the microscope proved of epoch- 
making significance. By its use Ehrenberg made the dis- 
covery that a number of widely distributed rocks, soft in 
character, such as chalk and tripolite, as well as certain lime- 
stones from the older formations, were entirely composed of 
the skeletons of lowly organisms (diatoms, foraminifera). 
Ehrenberg's work on chalk and chalk-marls was published 
at Berlin in 1839; fifteen years later, in his Mikrogeologie, he 
gave a complete account of his microscopic investigations on 
the composition of sedimentary deposits, the work being 
enriched by a very large number of excellent illustrations. 

Although Ehrenberg's method of microscopic examination 
of friable and earthy rock-material had been so eminently 
successful, it did not seem as if it could be adapted for the 
investigation of the harder rocks. The thin splinters of a 
crystalline rock were not sufficiently transparent even when 
imbedded in Canada balsam, and NicoFs optical method of 
identifying the mineral fragments was little known. Besides 
Nicol himself, David Brewster and Humphrey Davy interested 
themselves in the microscopical examination of the structural 
relations of minerals, and the frequent fluid inclusions of rock 
minerals. Scheerer in 1845 identified the hemicrystalline 
structure of many apparently homogeneous rocks, and in 
transparent chips of crystals examined by transmitted light 


he recognised numerous minute foreign bodies and inclusions. 
But these authors failed to make sufficient impression upon 
contemporary thought. Petrography continued to be con- 
ducted for the most part along the old lines ; in Germany the 
best known teachers of petrography were Rose, Cotta, Nau- 
mann, and Rath; in France, Delesse, Durocher, and Fournet. 
Naumanri's Lehrbuch contains an admirable representation of 
the state of petrography in 1850. But, instead of the sub- 
divisions then customary, Naumann differentiated rocks chiefly 
according to their origin as crystalline, clastic, hyaline, poriform, 
zoogene, and phytogene. 

In the following decade, the interest of petrographers was 
chiefly directed to the chemical side. Until that time, geology 
had troubled little about chemistry. The foundations of 
geology had been laid without the assistance of chemistry; 
among the leading geologists of the heroic period, only 
Hutton and De Saussure were learned in chemistry, and they- 
had not seemed to find much use for their intimate knowledge 
of that branch of science. Cordier had in 1815 applied 
hydrochloric acid for the determination of certain constituents 
of rocks, and Gmelin in 1828 had made an analysis of 
phonolite, separating the elements that were soluble in hydro- 
chloric acid from those that were insoluble. But a purpose- 
ful chemical investigation of rocks was first attempted by 
Bischof and Bunsen. 

Gustav Bischof (ante, p. 217), the founder of Chemical 
Geology, was much more a chemist than a geologist, and 
although his lack of sound geological knowledge could not 
affect his experimental chemical researches on rocks, it proved 
detrimental when he came to draw generalisations from his 
results. In the first volume of his Text-book of Chemical and 
Physical Geology, Bischof begins with the consideration of the 
water on the surface of the earth and in internal- cavities and 
joints ; after a detailed description of springs, he turns his 
attention to their temperature, their chemical ingredients, etc., 
and to the chemical changes which are set up in the rocks 
when water is brought into contact with them. The second 
volume is a complete chemical mineralogy and petrology, in 
which the mode of origin of the rocks receives a large share 
of attention. When he reviews his facts, Bischof arrives at 
conclusions of an ultra-Neptunistic tendency and quite 
erroneous. The work is of high value on account of the 


large number of careful rock analyses, which show the rela- 
tive admixture of the different rock-forming substances. 
By careful chemical analyses, Robert Bunsen succeeded in 
distinguishing between two volcanic magmas exuded from 
different vents in Iceland the one, a normal trachytic or 
acid magma, the other a normal pyroxenic or basic magma, 
and showed that from the combination of these all possible 
transitional varieties of eruptive rock might take origin. After 
the publication of Bunsen's paper in Poggendorffs Annakn in 
1851, geologists were so zealous in the chemical investigation 
of rocks, that almost a thousand chemical and mechanical 
analyses of rocks were forthcoming ten years later when Justus 
Roth prepared his tabular list of rock analyses. 

In the year 1850, Henry Clifton Sorby published a short 
communication on the Jurassic Calcareous grit, whose 
structure he elucidated by applying Nicol's methods of ex- 
amining thin rock -slices by transmitted light. In two further 
treatises in 1853 and 1856 Sorby tried to solve the problem of 
cleavage by similar means of examining thin sections of 
cleaved rock. These earlier writings of Mr. Sorby were the 
precursors of his famous memoir in 1860, which revolutionised 
the teaching of petrography. Independently of Sorby, Oschatz 
in Berlin had recognised the importance of preparing thin 
slices of rock for microscopic examination. On the yth 
January 1852, Oschatz exhibited a collection of fifty micro- 
scopic slides of mineral sections at a meeting of the German 
Geological Society, and again in 1854 at a Scientific Congress 
in Gottingen, but he did not succeed in arousing any great 

The turning-point was Sorby's classic paper on the micro- 
scopical structure of crystals, published in the Quarterly 
Journal of the Geological Society in 1858. This paper demon- 
strated the structure of rock-forming minerals with unprece- 
dented accuracy; it compared the natural mineral crystals 
with crystals artificially produced, and finally drew definite 
conclusions regarding the origin of the different rocks. Sorby 
was able to deduce from the presence of fluid, gaseous, 
crystalline, vitreous, and slaggy inclusions in crystals, the 
aqueous or volcanic origin of certain rocks, and thus brought 
to an end questions which had been for many years matters 
of dispute, and which could never have been solved without a 
precise knowledge of the mineralogical elements and ground- 


mass of rocks. Sorby's paper was no less than epochal in its 
effect, it appealed both to field geologists and to mineralogists, 
for it revealed the community of interest in the results which 
could be obtained by accurate microscopic examination of 

Sorby's method was applied by Websky, who examined thin 
sections of minerals by polarised light, and attained brilliant 
results. A happy circumstance brought Sorby's influence 
directly to bear upon Ferdinand Zirkel. In the year 1862, 
while at Bonn, Sorby personally initiated Zirkel into his 
methods of investigation, and inspired him with enthusiasm 
for the new field of research. 

Specimens of crystalline rocks from all parts of the world 
were secured by Zirkel, who submitted them to microscopic 
examination by transmitted and polarised light, and arrived 
at ever sharper definitions of the various inclusions, and the 
appearances displayed in polarised light. By his compre- 
hensive researches Zirkel established Sorby's methods upon 
a broader empirical basis, and he at the same time introduced 
the new methods in his teaching of petrography at Bonn 

There were still some incredulous voices : Vogelsang in 
1864 doubted the existence of glassy inclusions in the com- 
ponent ingredients of porphyry, and other rocks of non-glassy 
structure ; Laspeyres in the same year also disputed the 
glassy inclusions in porphyritic rocks of Halle, and even 
doubted the distinction between glass and water vesicles. 

The publication of Zirkel's Lehrbuch der Petrographie 
(Bonn, 1866) may be said to mark the culmination of the 
older methods, and the academical initiation of the new. In 
his text-book Zirkel embraced all that was known about the 
mineralogical and chemical composition, the structure, system- 
atic arrangement, the mode of occurrence and origin of the 
various rocks; he also described the crystallographical results 
which had already accrued from microscopic investigation, and 
indicated the far-reaching advantages opened up by the new 
direction of research. Zirkel's work removed all doubt 
regarding the value of the microscopic results for systematic 

Vogelsang, in his Philosophic der Geologic und Mikro- 
skopische Gesieins-Studien (Bonn, 1867), accepted the new 
teaching in full, and added much to the knowledge of the 


porphyritic series by his careful microscopic investigation of 
the larger mineral constituents and the ground-mass char- 
acteristic of different varieties. Vogelsang's observations on 
the processes of the consolidation of rock-magma, on the 
microscopical structure of slags, on "fluidal" structure, on 
microlites, and on conditions of devitrification, are clear and 
accurate. His illustrations are throughout of high excellence; 
and his proof, given in collaboration with Geissler, that certain 
liquid inclusions in minerals and rocks consist of liquid car- 
bonic acid, is a discovery that will ever remain associated with 
the name of this promising scientist, who unfortunately died 
before he reached his prime. 

Special memoirs were contributed by Zirkel on phonolite, 
on glassy and partially glassy rocks, and on leucite rocks. A 
very important work was his Untersuchung iiber die mikro- 
skopische Zusammensetzung und Struktur der Basaltgesteine 
(Bonn, 1870). In this work, Zirkel showed for the first time 
that the basalts and the lavas corresponding to them may be 
classified in three groups (felspar, nepheline, and leucite 
basalts), and that each of these three modifications can be 
identified by its constitution and structure, as well as by the 

A few months before the appearance of Zirkel's work 
on basalt, Tschermak had published a short but valuable 
paper on the microscopic differentiation of the minerals 
belonging to the augite, hornblende, and biotite group, and 
thus removed one of the chief difficulties in the identification 
of rock-forming minerals. 

The year 1873 was signalised by the almost simultaneous 
appearance of two works, in which the two most distinguished 
masters in the domain of microscopical research comprised 
the quintessence of their investigations. Under the title, Die 
mikroskopische Beschaffenheit der Mineralien imd Felsarten 
(Leipzig, 1873), Zirkel gives an introductory code of instruc- 
tions as to the use of the microscope, examination by means 
of polarised light, and the methods of producing faithful 
illustrations. He then describes the microscopical structure of 
rock-forming minerals with special respect to the various kinds 
of inclusions and the products of decomposition. The 
optical and physical characteristics of mineral sections are 
next described ; and the results obtained in the earlier 
chapters on minerals are applied in the latter half of the work, 


which is devoted to the mineral constitution and structural 
features of rock-varieties. The work is fully illustrated by 

The other important work was that of Rosenbusch, en- 
titled, Die mikroskopische Physiographic der petrographisch wich- 
tigen Mineralien (Stuttgart, 1873). It contains an exhaustive 
statement of the practical methods according to which rocks 
may be identified by means of the morphological, physical, 
and chemical properties of their component minerals ; this is 
followed by a full and methodical discussion of the microscopic 
characters of rock-forming minerals. The optical consideration 
of the phenomena of polarisation was elucidated so admir- 
ably by Rosenbusch, that his work created a secure basis for 
future petrographical researches. By the improvement of the 
microscope and the polarising apparatus, by the introduction 
of a rotating stage, and by other mechanical aids, it was now 
rendered possible to distinguish not only singly or doubly 
refracting bodies and uniaxial or biaxial minerals, but also to 
determine more accurately the specific optical properties of 
minerals belonging to the different systems of crystallisation. 
After the publication of this great work, Rosenbusch took 
rank along with Zirkel as one of the great pioneers in the 
microscopical investigation of rocks. In 1877, Rosenbusch 
published a second volume entitled Die mikroskopische 
Physiographic der massigen Gesteine. 

Rosenbusch distinguished the massive rocks according to 
the felspathic modifications: T, Orthoclase rocks; 2, Ortho- 
clase, nepheline, leucite rocks; 3, Plagioclase rocks; 4, Plagio- 
clase, nepheline, leucite rocks; 5, Nepheline rocks; 6, Leucite 
rocks ; 7, Non-felspathic rocks or peridotites. Each of these 
groups was subject to further sub-division according to the 
particular rock-structure, or in the case of the felspathic rocks 
according to the presence or absence of quartz. Like Zirkel, 
Rosenbusch gave due consideration to the geological age of 
the rocks, as the older and the younger representatives of each 
group were handled separately. 

The optical method brought to such a high point by 
Rosenbusch was still further elaborated by Bertrand, Klein, 
and Lasaulx in memoirs which appeared in 1878. Schuster 
proved in the following year that the felspars which had 
been recognised in such a masterly way by Tschermak from 
their composition to be isomorphous mixtures, represented a 


series of closely-related modifications which could be optically 

In addition to the service rendered by microscopic methods 
in facilitating the accurate mineralogical identification of 
the chief constituents of rocks, these methods disclosed the 
existence of a considerable number of subordinate mineral 
constituents which had either been wholly overlooked by 
macroscopic research or had been supposed to be extremely 

To mention one example, augite was found to be present in 
granite, porphyry, rhyolite, "phonolite, etc. This discovery was 
a direct contradiction to previous teaching that certain minerals 
could not exist in association with each other in the same 
rock; amongst other couples quartz and augite, orthoclase and 
augite, leucite and plagioclase, had been said to be mutually 

Microscopical research made it possible for the first time 
to attain a clear conception of the different kinds of rock- 
structure. The composition and structure of the ground-mass 
in hemicrystalline rocks was revealed, and new light was 
thrown upon characteristic structures of glassy rocks, fluxion 
structure, spherulitic and perlitic structure. Hence with the 
aid of the microscope the origin of the crystalline rocks began 
to be better understood, and their relations to the group of 
apparently homogeneous rocks. 

The indifference with which the large body of geologists 
had long viewed the microscopic study of rocks now gave 
place to zealous interest, and from the year 1870 the very 
large number of special papers that were devoted to 
petrological subjects not only filled Mineralogical Journals, 
but occupied a large share of the space in the Journals of 
Geological Societies. The sudden influx of new literature was 
unprecedented, and it would be hopeless to attempt to men- 
tion individual papers in the present work. Between 1870 and 
1880, two-thirds of the publications on microscopic petro- 
graphy belonged to Germany and Austria. Amongst British 
workers Allport, Rutley, Houghton, Bonney, Archibald Geikie, 
Teall, Harker, may be named ; in North America some of the 
pioneers were A. Hague, Whitman Cross, Iddings, G. H. 
Williams, Wadsworth, Lawson. 

The results of these researches necessitated many changes in 
the systematic arrangement of the rocks, and in no group was 


the influence of microscopic study more revolutionary than 
in that of the massive rocks. Zirkel, in 1866, classified the 
massive crystalline rocks mainly upon the basis of the modi- 
fications of felspar, and sub-divided them into five chief 
groups orthoclase, orthoclase and oligoclase, nepheline and 
leucite, labradorite, anorthite rocks. The orthoclase and 
oligoclase group was sub-divided into rocks containing quartz 
and rocks without quartz, and the members of the sub-groups 
were further distinguished by the presence or absence of 
hornblende or augite, or of different modifications of felspar. 
The geological age and the structure (granitic, porphyritic, 
glassy) afforded additional means of differentiation. 

Notwithstanding the great success that attended the micro- 
scopic study of rocks, certain mineral elements could not be 
identified by the finest optical methods, and it was felt 
necessary to combine microscopic and chemical investigations. 
Micro-chemical methods were invented for the purpose of 
testing the composition of minute mineral grains ; excellent 
memoirs dealing with this branch of research were published 
by Streng, Boricky (1877), Behrens, Haushofer (1883-85), and 
by Klement and Renard (1885). 

Cordier had in 1815 introduced a mechanical means of 
separating the fine particles of mineral matter by reducing 
them to powder, washing the powder with water, and allowing 
the mineral particles to subside according to their respective 
specific gravities. An additional device for the isolation of 
the fine particles was communicated in 1875 by Fouque, 
who pulverised specimens of the Santorin lava and then 
used a strong electro-magnet to attract the mineral particles 
.containing iron. 

A more signal improvement in mechanical means of isolation 
had been suggested in 1862 by Count Schaffgotsch, and 
afterwards by Church. It was proposed to introduce finely 
powdered mineral matter into a saturated chemical solution, 
such as the solution of iodide of mercury and potassium, 
prepared by Thoulet, and to shake the mineral powder in 
the solution, so that the particles which are heavier than the 
solution will sink to the bottom while the lighter particles will 
float. By diluting the original solution, or using other solu- 
tions of given density, the particles can be obtained successively 
according to their specific gravities. Since Thoulet conducted 
his experiments, solutions of greater density have been pro- 


posed by Klein, Breon, Rohrbach, and others, and have been 
used for the purposes of separation. 

The important results of microscopical and micro-chemical 
search were incorporated in the German text-books of Lasaulx 
(1875) an d O. Lang (1877); while the admirable work of 
Rosenbusch more especially gave an impulse to the study of 
petrography in other countries. In France, two illustrious 
petrographers, Fouque and Michel-Levy, adopted the improved 
methods and advanced scientific research by many valuable 
contributions. From the year 1873, both devoted themselves 
to the artificial preparation of silicates, and made a comparison 
of the artificial products with the natural occurrences in rocks; 
while Fouque developed principally the crystallographical 
aspects of microscopic investigations, Michel-LeVy devoted 
himself more to the microscopic study of the petrographical 
relations. In 1879, their conjoint work on the French Eruptive 
Rocks appeared in the form of an explanatory text to the 
detailed geological map of France. 

In this work MM. Fouque and Michel Levy followed 
the general arrangement of the Microscopic Physiography of 
Rosenbusch. The French authors distinguished original and 
secondary minerals in rocks ; the former are said to be present 
sometimes as essential, sometimes as accessory constituents ; 
the secondary are sub-divided according to the time of their 
generation into two main groups, and these are again divided 
into sub-groups. The rocks are classified with respect to their 
origin, their geological age, their mineralogical composition, 
and their structure. The massive rocks of pre-Tertiary epochs 
are held distinct from those of Tertiary and recent ages, and 
certain differences are indicated between them. MM. Fouque 
and Michel-Levy recognise two leading types of structure among 
the massive crystalline rocks, the granitoid and trachytoid ; 
these terms almost correspond to the use of the terms 
granular-crystalline, and porphyritic in the works of the 
German petrographers. 

The French authors bring into pre-eminence the mutual 
development attained by the several elements in the rocks. 
Their special study of this feature has led them to believe 
that many massive rocks give evidence of the generation of 
crystals or crystalline material in successive phases of consolida- 
tion. In both the granitoid and trachytoid types, the larger 
crystals are generated during the first phase of consolidation. 


A second phase of consolidation is marked by the generation 
of smaller crystals of microlites or a microlitic ground-mass. 
The development of crystallites and ground-mass at this phase 
is limited to trachytoid rocks. 

In the case of granitoid rocks the consolidation is complete 
at the close of the second stage, but in the case of trachytoid 
rocks there follows still a third phase characterised by processes 
of alteration in the crystals and matrix already formed, and by 
the constitution of a micro-felsitic, microlitic or glassy ground- 

For the identification of the individual rock-varieties MM. 
Fouque and Levy regard the felspars of primary import- 
ance ; subordinate means of identification are afforded by the 
magnesia - iron silicates (mica, hornblende, augite, diallage, 
hypersthene, peridote). The work concludes with a detailed 
description of the rock-forming minerals. In France, the 
Fouque-Levy system has held an authoritative place in the 
teaching of petrography. 

A second edition of his Mikroskopische Physiographic der 
petrographisch wichttgen Mineralien was produced by Rosen- 
busch in 1885. Rosenbusch had practically re-written this 
work, and made it an exhaustive compendium of all the results 
obtained by microscopical, crystallographical, and micro- 
chemical methods. The optical phenomena of crystallography 
were discussed with the utmost care. In the first edition 
Rosenbusch had advanced microscopical research by the intro- 
duction of new apparatus, in the second he was able to add 
many valuable mineralogical results of the improved means of 
research. He also gave full and precise instructions regarding 
the use of the microscopic methods, so that by following the 
directions given in this work any earnest student might become 
a proficient crystallographer and mineralogist. 

In 1888, Michel-Levy and Lacroix published Les Mineraux 
des Roches^ a work which provides an excellent general account 
of all the physical and optical properties of rock-forming 
minerals, and, like that of Rosenbusch, gives full directions 
for the optical examination of thin sections, and for all micro- 
chemical means of identifying mineral fragments. The French 
authors relied in many cases on the crystallographical investi- 
gations of Descloiseaux, and also incorporated many of the 
methods and results of Rosenbusch. 

Although Sorby had been the great pioneer of modern 


petrography, the geologists of Great Britain were not to the 
front in continuing and advancing the new line of research. 
It was not until Zirkel and Rosenbusch in Germany, and Fouque, 
Michel-Levy, and Lacroix in France, had elaborated the new 
system of research, and spread its teaching in the universities 
by their text-books, that Great Britain took a more animated 
part in the pursuit of petrography. 

In 1888, Mr. Frank Rutley published a book on Rock-forming 
Minerals, in which he described the optical and chemical 
properties displayed by the different minerals on microscopic 
investigation. In the same year a book on British Petrography 
was published by Mr. J. J. Harris Teall. The chief purpose of 
the handbook was to bring the newest methods and results 
of petrological research within the reach of a large circle of 
British students and geologists. The work deals with the 
eruptive rocks that occur in Great Britain; it begins with a 
lucid discussion of ground-mass and the rock elements that can- 
not be mineralogically identified. Frequent reference is made 
to the investigations of Sorby and Vogelsang. The chemical 
composition of the eruptive rocks is fully treated, having 
respect to the researches of Bunsen. In discussing rock- 
texture, Mr. Teall attributes great importance to the size and 
development of the individual mineral components. The 
features enumerated as valuable for the systematic arrange- 
ment of the rocks are (i) the chemical composition, (2) the 
mineralogical composition, (3) the texture, (4) the occurrence, 
(5) the origin, (6) the geological age, (7) the locality. As, 
however, the chemical composition cannot be judged from a 
hand-specimen, Mr. Teall applies the mineralogical composition 
as the primary means of classification, and uses texture for the 
differentiation of sub-groups. The work concludes with very 
valuable remarks on the origin and the metamorphoses of the 
crystalline massive rocks. 

During the same year Rosenbusch published a second edi- 
tion of his Mikroskopische Physiographic der massigen Gesteine, 
In this edition he entirely withdrew his former principle of 
classifying the rocks primarily on the basis of their mineralogi- 
cal composition. Laying down as a fundamental principle 
that a natural classification of the rocks ought to reflect the 
genetic relations, Rosenbusch contended that rock-structure 
offered the most reliable basis for the construction of a natural 
system of the massive rocks. He pointed out that the struc- 


ture of the eruptive rocks is dependent upon the conditions of 
their geological occurrence, and classified them accordingly in 
three chief groups : deep-seated or " plutonic " rocks, intru- 
sive or "dyke" rocks, and eruptive flows or "sheets." This 
new standpoint assumed by Rosenbusch re-acted upon the 
whole newer development of petrography. By subordinating 
in his new system all considerations of the chemical and 
mineralogical composition, and the geological age, to the 
mode of occurrence of eruptive rocks in nature, Rosenbusch 
removed as it were the final judgment of petrography from 
the laboratory to the field. The petrographer was made to 
feel that the microscope and chemical re-agents were to be 
regarded as aids to field observations, but that systematic 
interest was to be concentrated upon the problems dealing 
with rock-structure in its relation to particular conditions of 
stratigraphical occurrence. In this direction original research 
seemed to give most promise of enlightenment in the imme- 
diate future. 

Rosenbusch introduced a number of new descriptive terms, 
e.g., holocrystalline, hemicrystalline, hypidiomorphic, panidio- 
morphic, etc., for the purpose of defining all structural modifi- 
cations with scientific accuracy. According to Rosenbusch, 
the deep-seated eruptive rocks are all distinguished by holo- 
crystalline and hypidiomorphic granular structure. They have 
originated at great depths of the crust by slow processes of 
cooling and consolidation. He divides them into sub-groups 
which are based upon the presence and relative amount of 
quartz and felspar; in this respect, therefore, Rosenbusch 
adopted the system of MM. Fouque and Michel-Levy. 

Rosenbusch includes in his group of intrusive rocks those 
eruptive masses which occur in the form of typical dykes, yet 
are to be regarded only as particular facies of deep-seated 
eruptive rocks, and may probably be associated with the latter 
in their genesis and their distribution in the crust. The intru- 
sive group is sub-divided into three series a granitic, a 
syenitic, and a dioritic, whose characteristic types of structure 
are quite independent of their mineralogical composition. 

Porphyritic structure is said by Rosenbusch to be character- 
istic of eruptive sheets; the constituents belong to at least 
two successive generations. He thinks it probable that the 
older constituents represented by the larger crystalline ele- 
ments are intra telluric in origin, and may have formed at 



great depths previously to any surface eruption of the magma; 
whereas the younger and minute mineral elements probably 
originated during the epoch of eruption. With the outflow 
of a glowing rock-magma at the surface, and the escape of the 
water vapours, the chemical constitution of the rock-material 
is changed. The structure of the ground-mass is holocrystal- 
line, hemicrystalline or glassy, according to the more rapid or 
slower cooling of the magma. 

Rosenbusch sub-divides the rocks of eruptive flows into 
palceovolcanic (porphyry, porphyrite, augite porphyrite, mela- 
phyre, and picrite porphyrite) and neovolcanic (liparite, trachyte, 
phonolite, andesite, basalt, etc.). Some of the older flows, 
such as the diabase porphyrite and picrite porphyrite, resemble 
granitic-porphyritic intrusive rocks so closely that they seem to 
bear the same relationship to them which the typical intrusive 
rocks bear to the plutonic or deep-seated masses. They may 
be distinguished from true eruptive flows by the absence of 

The new classificatory scheme of Rosenbusch showed quite 
clearly that he had been strongly influenced by the views of 
MM. Fouque and Michel-Levy, and these two French petro- 
graphers felt it incumbent to declare the position they assumed 
towards it. In 1889, Michel-Levy discussed the work of 
Rosenbusch in a special memoir, agreeing with many of its 
principles, but disputing others. Regarding the sub-division 
of the eruptive rocks into deep-seated masses, intrusions, 
and flows, Levy points out that the intrusive group is quite 
artificial and untenable, as intrusions may either take the 
form of narrow vertical dykes or almost horizontal sheets or 
"sills." He also contests the conclusion of Rosenbusch that 
only one generation of the crystalline constituents took place 
in the deep-seated rocks, a group which almost precisely 
corresponded with the granitoid group of MM. Fouque and 

In Michel-Levy's opinion, the geological aspects and associa- 
tions of the eruptive rocks, as well as the geological age, have 
too little connection with the structure of the rocks to provide 
a good basis of classification. Michel-Levy cites cases where 
rocks belonging to the "deep-seated group" of Rosenbusch, 
e,g., granite, ophite, and gabbro, occur in the form of eruptive 
sheets. According to Michel-Levy, the different types of 
structure in eruptive rocks are due to variations of temperature 


and pressure, and the saturation of the magma with gases and 
heated vapours. The latter play the chief role in the acid 
rocks, producing pegmatitic, micro-pegmatitic, and other 
structural types, and also determining a definite sequence of 
eruption. On the other hand, the structure of the basic rocks 
depends almost exclusively on temperature, i.e., on the greater 
or less rapidity of the process of cooling. 

After this adverse criticism of the classification advanced by 
Rosenbusch, Michel-Levy proceeds to discuss the varieties 
of rock-structure, and shows the frequent agreement between 
the views of Rosenbusch and his own; he also points out 
that the differences of nomenclature are more apparent than 
real, and tries to bring the French and German terminology 
into harmony by means of a list of synonyms. In most cases, 
Michel-Levy claims the priority for his own terms. 

Only a few minerals come into question in the composi- 
tion of eruptive rocks. Fouque and Michel- Levy had classed 
these minerals as original and secondary, sub-dividing the 
secondary minerals in groups corresponding with the order of 
formation. According to Rosenbusch, there are just two 
fundamental laws controlling the order of formation the one, 
that the magma is always more acid than the sum of the 
mineral constituents already solidified in it; and the other, that 
the separation of the elements which occur in less profusion 
has generally been concluded before the separation of the 
more richly distributed elements takes place. Michel-Levy 
questions the correctness of these laws, and makes an elaborate 
inquiry into the order of separation of the mineral con- 
stituents. He devises a code of symbols by which the 
structure, composition, and genesis of the massive rocks may 
be represented by a short formula ; and finally arrives at the 
conclusion that the classification and the nomenclature of 
eruptive rocks must be kept free from any hypothesis re- 
garding their origin, and consequently that structure and 
mineralogical composition form the only basis of a rational 

Zirkel assumed a similar standpoint in the second edition of 
his Lehrbuch der Petrographie (1893-94). This large three- 
volume work is the only complete handbook of petrography. 
All varieties of eruptive, schistose, and sedimentary rocks are 
treated according to their macroscopic, microscopic, and 
chemical constitution, their structure, and their geological 


occurrence. The diction is clear, the previous literature of 
petrography has been completely mastered, and its results are 
fully incorporated, the historical development of the different 
branches of the study being carefully indicated throughout the 
work. The lack of illustrations has been deplored by many, 
but the addition of plates would have rendered the work much 
more expensive. 

The first volume begins with a detailed account of all 
methods of investigation applied in modern petrography. 
Rock-forming minerals are then described according to their 
morphological, optical, physical, and chemical properties so 
far as these are important for petrography. In discussing the 
structure of rocks, Zirkel frequently dissents from the 
terminology of Rosenbusch ; at the same time he endeavours 
to establish the terms which had been applied in his own 

The special petrographical part of the work starts with the 
treatment of the massive rocks formed by the cooling and 
consolidation of molten magmas. The geological occurrence, 
the composition, the macroscopical and microscopical features 
of their structure, are elucidated. The difficult questions 
concerning ground-masses are then brought forward, and 
finally the laboratory experiments are described by means of 
which chemists and geologists have tried to produce different 
kinds of massive rocks artificially. 

Zirkel contests the principle of classification adopted by 
Rosenbusch, and adduces weighty arguments to show that the 
group of "intrusive" or "dyke" rocks is intenable. He 
adheres to the principle of mineralogical composition as the 
true basis of classification, and draws up a Classification Table 
on the same lines as he had followed in the first edition of 
his text-book. Zirkel's sub divisions agree in many respects 
with those of Fouque and Michel-LeVy. Taking the felspathic 
constituents as the chief standard, Zirkel distinguishes two 
felspar-bearing groups, a potash-felspar group, and a soda-lime 
felspar group; also a third group, free from felspar, and 
comprising the nepheline, leucite, melilite rocks. 

Like Michel-Levy, Zirkel distinguishes two leading types of 
structure: i, uniformly granular; 2, porphyritic and glassy 
rocks. Deep-seated rocks of various geological ages belong to 
the granular or granitic type ; while eruptive flows may be 
either porphyritic or glassy, and they may be sub-divided 


according to age as pre-Tertiary ( Pal aeo volcanic), and Tertiary 
and Post-Tertiary (Neovolcanic). 

The second and third volumes of the text-book are devoted 
to an exhaustive description of the individual varieties of 
massive and schistose crystalline rocks and the sedimentary 

Zirkel's text-book will always remain a fundamental work 
in petrography. While the macroscopic methods of the 
older teaching are still predominant in the first edition of the 
work, the second edition is at once a frank and full 
acknowledgment of the petrographical reform necessitated by 
microscopic and micro-chemical methods, and a convincing 
witness of the rapid and remarkable success which had 
crowned the labours of petrographers in the new field of 

During the last few years the discrepancy between the views 
of Zirkel and Rosenbusch has increased. Rosenbusch, in the 
third edition of his Physiographic der massigen Gesteine (1896), 
and also in his Elementender Gesteinslehre(\%$], has adhered 
to the standpoint which he assumed in 1888, and has rejected 
Zirkel's objections. The differences between the two leading 
German petrographers refer in no sense, however, to the 
methods of investigation, but expressly concern the inductive 
conclusions at which they have arrived regarding the genesis 
of the eruptive rocks, and the best system of classification. 
The rapid progress of petrography is one of the greatest 
acquisitions made to science during the latter half of the 
nineteenth century, and has elevated petrography to the rank 
of a thoroughly established branch of natural philosophy. 

As the microscope revealed more and more fully the fine 
structure and microscopic elements, of rocks, the traditional 
conceptions of geologists regarding the origin of the rocks 
were gradually undermined. The old strife between Plutonists 
and Neptunists had collapsed when the Neptunists admitted 
the volcanic origin of basalt and the "trap" series of rocks. 
The handsome monograph published by C. C. von Leon- 
hard in 1832 had conclusively proved the agreement of 
basalt with true volcanic rocks, both in the geological 
occurrence of the basalt and in the contact phenomena 
produced at its margins. Thanks to the observations of 
Humboldt, Buch, Poulett-Scrope and others, not only was 
the volcanic origin of basalt, trachyte, trap, porphyry, mela- 


phyre, phonolite, and related rocks generally recognised, 
but also Huttonian views respecting the plutonic origin of 
the granite-grained massive rocks became more widely 

Nevertheless, new objections were raised against the 
pyrogenetic origin of the granite-grained rocks. Keilhau 
asserted in his work on the "transitional formations" of 
Norway that the granite in that area had originated from the 
conversion of clay slates. The Munich chemist, Johann 
Fuchs, in 1837 attacked the doctrine of pyrogenetic origin in 
a series of papers entitled Ueber die Theorien der Erde. He 
pointed out that fusion experiments had never succeeded in 
reproducing granitic rock artificially, even although individual 
elements of the rock had been obtained; further, minerals 
having different melting-points were present in granite, yet 
these minerals had not consolidated from the magma in the 
order that corresponded with that of their fusibility, therefore 
he argued it was absolutely erroneous to suppose that granitic 
rock had formed merely as the result of slow cooling and 
consolidation. Fuchs advanced the view that granite, and the 
granitoid rocks generally, had consolidated from an amorphous 
magma saturated with water. 

In 1845, Schafhautl succeeded in reproducing quartz 
artificially by the application of superheated water in a Papin 
crucible, and this result seemed to confirm Fuchs' views. On j 
the other hand, Fournet, in 1844 an< 3 1847, pointed out that 
there were certain conditions under which the fusing-points of 
substances were lowered to temperatures much below the 
points at which they usually solidified. In papers written 
about the same time, Durocher, referring for support to 
Fournet's Theory of surfusion, supposes a mass of granite to 
be originally a homogeneous magma, which can remain fluid 
until the fusion temperature of felspar is almost reached. 
At about 1500 C. the separation of felspar, quartz, and 
mica begins, and the different minerals solidify according to 
their tendency to crystallisation. Durocher thinks the later 
formation of quartz crystals might in this way be explained, 
since felspar passes more readily than quartz from the viscous 
to the solid state. 

Scheerer, the illustrious chemist and geologist, offered 
formidable objections to the purely pyrogenetic origin of 
granite in a memoir published in the Bulletin of the French 


Geological Society in 1847. His chief arguments were: (i) the 
occurrence of separated quartz ; this, according to Scheerer, is 
impossible in the case of consolidation from a fluid mixture of 
silicates; (2) the order of succession in the separation of 
felspar and quartz ; Scheerer ascribes no weight to Fournet's 
"surfusion" theory, which supposes that quartz can remain 
longer in solution than the more easily fusible felspar, as this 
is a hypothesis which has not been tested experimentally for 
silicate mixtures ; (3) the presence of so-called pyrognomic 
minerals (orthite, gadolinite), whose physical properties are 
altered at comparatively low temperatures. 

Scheerer also drew attention to the fact that water is held 
in chemical combination with several of the constituents of 
granite. This water he regarded as originally present in the 
magma from which the granite solidified. But if the magma, 
as might be safely assumed, was subjected to high pressure, 
which prevented the escape of the superheated water, then 
very probably the influence of the water might enable the 
granite magma to remain fluid at temperatures much lower 
than would be the case under the influence of dry heat. 
When solidification set in, the minerals with the strongest 
tendency to crystallise were the first to separate from the pasty 
granite mass, and the water concentrated itself in the remaining 
ground-mass, which always became more acid, and owing to 
the superfluity of water the separation of quartz and the 
pyrognomic minerals might under some circumstances be 
suspended until the temperature of the mass was below that 
of a red heat. 

Although Durocher still upheld the pyrogenetic origin of 
granite against the objections raised by Scheerer, the hydato- 
pyrogenetic or aquo-igneous doctrine ef Scheerer rapidly gained 
ground in literature. Probably its strongest antagonist was 
Bischof, whose explanation of the origin of granite, syenite, 
porphyry, and even basalt, showed a reversion to Neptunistic 
teaching. In the second volume of his Physical and Chemical 
Geology (1851), Bischof, after a full discussion of the rock- 
forming minerals, came to the conclusion that all except 
augite and leucite could take origin from aqueous solutions 
without increased temperature and under normal pressure, 
and that their origin from fused rock-masses was quite excep- 
tional. Moreover, the resemblance between the composition 
of many eruptive rocks and that of certain sedimentary rocks 


(slate, greywacke), as well as the interbedding of granite with 
gneiss and sedimentary schists, led Bischof to agree with the 
opinion of Keilhau (1825) and Virlet d'Aoust (1846), that 
granite and syenite represented altered clay slates. Diabase 
and even" melaphyre and basalt were regarded by Bischof as 
shales and clays, poor in silica, and altered by the agency of 

C. W. C. Fuchs, in 1862, supported Bischof's views in a 
valuable treatise on the mineralogical and chemical consti- 
tution of the granite in the Harz mountains. He regarded 
the granite as a product of the alteration of sedimentary grey- 
wacke by means of water, hornstone being formed in the 
earlier phases of alteration, and granite during the later 
phases; these two rocks were connected by a transitional 
series of alteration products. 

A serious objection to the pyrogenetic origin of granite was 
advanced by H. Rose in 1859. He showed that after fusion 
quartz passes into an amorphous modification of silica, thereby 
changing its specific gravity from 2.6 to 2.2. As the quartz in 
granite and granitoid rocks always has a specific gravity of 
2.6, it seemed impossible to suppose it had merely separated 
from a dry fused mass. 

The aquo-igneous origin of granite suggested by Scheerer 
on theoretical grounds was soon to receive an experimental 
conformation. Struck by the peculiar changes which sedi- 
mentary deposits underwent in contact with, or in the near 
vicinity of, eruptive rocks, Professor Daubree attempted to 
show that neither heat alone, as Hutton had supposed, nor 
vapours and gases would suffice to call forth these changes, 
but that superheated water under great pressure was the most 
important agent in the metamorphism of rocks. To prove this 
hypothesis, Daubree in 1857 conducted a series of very 
instructive experiments. A glass tube partially filled with 
water, and hermetically sealed at both ends, was placed in a 
strong iron tube, which was then closed and exposed to a 
temperature slightly below red heat. After a few days the 
glass tube was attacked ; in parts of it a finely laminated 
structure was induced, and the whole tube was transformed 
into a zeolitic mineral, in virtue of the removal of silica, alumina 
and soda, and the addition of water. Innumerable small crystals 
of quartz formed; microlites and diopside crystallites developed 
in abundance in the less violently attacked parts of the tube, 


and spherulitic structure was present in some places. In other 
experiments where Daubree applied superheated steam, he 
obtained orthoclase and a micaceous substance. These ex- 
periments gave convincing evidence that the constituents of 
granite could be of aquo-igneous origin. 

Almost simultaneously with Daubree's investigations, Sorby 
was engaged in microscopic examination of thin sections of 
granite. He demonstrated, in 1858, the presence of water 
vesicles in quartz, and concluded that the granite magma had 
been saturated with water and had solidified under great pres- 
sure at a temperature not above a dull red glow. Delesse, 
in 1857, drew attention to the great differences between the 
phenomena of contact metamorphism produced by granite and 
those produced by lavas, and argued from his observations 
that the granites had not solidified from a state of dry fusion, 
but from an eminently plastic magma, whose plasticity was due 
to the presence of water under high pressure. The theory of 
the aquo-igneous origin of granite, and of the granite-grained 
massive rocks generally, began to win wider credence in geo- 
logical circles. 

The rapid progress made by microscopic research after the 
year 1860 entirely disproved all theories which had assumed 
an aqueous origin for porphyritic rocks. Examination of 
thin sections showed conclusively that basalt, phonolite, 
trachyte, porphyry, etc., were identical in internal structure 
and composition with true volcanic lavas. Corroborative 
evidence was afforded by the experimental researches which 
were conducted, more especially in France, with such eminent 
success. The attempts to reproduce rock-forming minerals 
artificially proved that the majority of the constituents in the 
granitic rocks, such as quartz, orthoclase, microcline, potash 
mica, tourmaline, hornblende, could be solidified from fused 
materials by the admixture of water vapours, chlorine, and 
other solvents, whereas the minerals occurring in volcanic 
and porphyritic rocks, such as olivine, augite, enstatite, 
hypersthene, wollastonite, the plagioclase varieties, melilite, 
nepheline, leucite, magnesia mica, garnet, magnetite, spinel, 
haematite, tridymite, etc., could solidify from a state of dry 

In the year 1878, the efforts of Fouque and Michel-Le'vy to 
reproduce eruptive rock without the aid of superheated water 
were at last successful. The chemical elements were placed in 


a platinum crucible and fused; the fused mass was then sub- 
jected for forty-eight hours to a temperature nearly that of the 
fusing-point, the material being afterwards allowed to cool 
slowly. According to the ingredients that were introduced, 
consolidated rock-material agreed completely with certain 
augite-andesites, leucite and nepheline rocks, and contained 
the majority of the minerals composing these rocks in the 
form of well-developed crystals. 

Inasmuch as these important results showed that the por- 
phyritic series of rocks could originate merely by the cooling 
of a molten magma, they tended to widen the gulf between 
the porphyritic and basaltic, and the granite-grained series. 
Favour was given to Hutton's assumption that the latter owed 
their distinctive characters to their subterraneous origin under 
great pressure, and the Huttonian conception was made even 
more emphatic by Rosenbusch in his classification of 1886. 
Further confirmation was given by Gilbert's description of 
intrusive masses of rock, so-called "laccolites" (ante, p. 274) 
between sedimentary strata in the Henry mountains ; and also 
by Reyer's investigations on massive flows and local differences 
in the mineralogical composition and the texture of the con- 
solidated rock. 

After the principle of the eruptive origin of the crystalline 
massive rocks had been firmly established, the interest of 
petrographers was directed to the investigation of the chemical 
constitution of the rock-magmas and the processes effecting 
their consolidation. The chemistry of rocks had been greatly 
advanced by the researches of Abich, Delesse, Bischof, 
and especially by Bunsen. As has been already mentioned 
(ante, p. 328), Bunsen concluded from his examination of the 
igneous rocks of Iceland that all the eruptive rocks of that 
island in their composition presented either a normal trachyte 
magma or a normal pyroxene magma, or a mixture of these 
two varieties of rock-magma in varying proportions. According 
to Bunsen, it is possible by means of a simple formula, being 
given the amount of silica present in such a mixed rock, to 
reckon the amount of the normal trachytic and normal pyro- 
xenic material present in the rock. Streng, Kjerulf, and others 
accepted Bunsen's conclusions and tried to apply them gene- 
rally to all eruptive rocks. 

Sartorius von Waltershausen explained (1853) the chemical 
difference of the Iceland eruptive rocks, not upon Bunsen's 


theory of their origin from two different subterranean localities, 
but upon the assumption of their origin at different depths of 
the crust. He held as a general principle that subterranean 
magmas are distributed in the crust according to their specific 
weight, the lighter magmas rich in silica occupying the crust- 
cavities in the higher zones, the heavier basic magmas occurring 
at lower horizons. Durocher, in 1857, gave a similar explana- 
tion of the chemical and mineralogical differences in rock- 

On the other hand, Poulett-Scrope (1825), Darwin (1844), 
and Dana (1849) attributed the varieties of eruptive rocks to 
the subsequent division and differentiation of a homogeneous 
primitive magma. Justus Roth (1869) also regarded all 
plutonic rocks as having been derived from a uniform 
primitive magma, and explained their present differences of 
constitution as a result of the different rates of cooling. 
Iddings more recently remarked on the fundamental mineral- 
ogical affinity of the different rock varieties in an eruptive 
district, and compared such resemblances with the blood 
relationships of organisms. Although most geologists at the 
present day incline to the opinion that the different facies of 
eruptive rock represent portions of a single primitive magma, 
there is still great variance of opinion regarding the mode of 
division and differentiation. 

The experiments of Spallanzani, Hall, and Bischof showed 
that by means of regulating the process of cooling, or by 
the application of different degrees of pressure, fused silicate 
mixtures could be obtained in glassy, slaggy, or crystalline 
rock-form. By Daubree's experiments it was ascertained that 
the conditions requisite for the artificial reproduction of 
granite-grained eruptive rocks were a moderate temperature 
and the presence of water vapour. Again, the experiments of 
Fouque and Levy seemed to show that the younger eruptive 
flows with porphyritic structure had solidified slowly from an 
igneous magma. It has proved a very complex and difficult 
question to find out what determines the particular sequence 
in which the rock-forming minerals separate from a viscous 
magma. Fournet and Bunsen showed that the minerals by 
no means separated from the magma in the order of their 
fusing-points. After various attempts to solve the problem by 
direct methods, it was then approached indirectly: keeping in 
view the essential constituents of any particular rock, attempts 


were made to separate from them any mineral elements which 
were foreign to the rock, or had come into the magma before 
it solidified, and also all secondary elements which had formed 
after the consolidation of the rock during the processes of 
internal decomposition or interaction. 

Excellent work has been done in this field of research by 
Roth, Bischof, Delesse, Zirkel, Broegger, and Iddings. 

Certain principles are usually inculcated regarding the 
sequence in which the minerals take origin during the passage 
of a magma from the viscous to the solid state, but the prin- 
ciples are by no means always applicable, and have therefore 
frequently been contested. Minerals which have crystallised 
with the most complete and perfect form have usually been 
regarded as the first-formed, while those which appear to 
have been checked in their proper development by others, 
have been regarded as of later formation. Again, minerals 
that are enclosed within other minerals are usually taken to 
be older than the enveloping material, yet cases are cited 
where they are really younger, having separated out from a 
portion of the magma enclosed within the developing mineral. 
Minerals without any inclusions for the most part belong to 
the first generation of solid material. If two minerals occur 
as intergrowths with one another, contemporaneous generation 
is indicated. In rocks with porphyritic structure the larger 
mineral forms are as a rule older than the ground-mass. 

It was in accordance with these principles that Fouque 
and Michel-Levy first distinguished different generations of 
minerals, and used the number of the mineral generations as a 
distinguishing feature between rocks of granitic and porphyritic 
structure. Through a large number of individual observations 
it -has been possible to determine genetic series for the rock- 
forming minerals. Certain minerals, such as magnetite, 
titanite, rutile, apatite, zircon, spinel, olivine, belong generally 
to the earliest products of separation, preceding the augites, 
hornblendes, felspars, and quartz. Rosenbusch holds the 
opinion that in the deep-seated rocks, at any one interval of 
time, there is only one kind of mineral separated from the 
magma. The periods of formation for the different constituents 
succeed each other so that either those of one kind do not form 
until the complete separation of the preceding kind; or much 
more frequently, a younger constituent in order of separa- 
tion begins to form a certain time before the completion of the 


next oldest constituent. In general, solidification begins with 
the crystallisation of the ores and accessory constituents, then 
follows the formation of the coloured silicates (olivine, mica, 
augite, hornblende, etc.), then that of the felspathic minerals, 
and finally that of free silica. In the rocks of eruptive flows 
the more basic constituents crystallise out before the less basic, 
so that at any period during the consolidation the sum of the 
constituents already crystallised out from the magma is more 
basic than the remaining portion of the magma. 'Mr. Teall 
assumes that in the rocks with a large or medium amount of 
silica, the dissolved constituents represent a so-called " eu- 
tectic " mixture, and as such can. remain unchanged at a 
temperature which is below their melting-point. But if they 
do not occur in the definite eutectic relations, the overplus 
of substances continues to separate out until . the eutectic 
mixture is attained. 

In an important memoir (1887) on the crystallisation of 
igneous rocks, Lagorio classified the porphyritic flows accord- 
ing to the amount of silica in five grades, and gave the results 
of chemical analyses of the ground-mass. He arrived at the 
conclusion that the separation of the minerals in an eruptive 
magma depends almost entirely on the chemical composition 
of the magma, as well as on the affinities and internal move- 
ments within the mass ; whereas pressure and high temperature 
exert only a subordinate influence. 

Iddings in 1889, in a paper on the same subject, expressed 
views in many respects similar to those *of Lagorio, but 
ascribed greater importance to the influences of pressure and 
temperature in regulating the rate and processes of cooling ; 
he thinks the local conditions of pressure and temperature 
mainly determine the structural differences which often exist 
at different portions of a continuous mass of eruptive rock, 
and explain why a superficial portion may display porphyritic 
structure while the deep-seated portion is granite-grained. 

There .are abundant examples of transitional rock-varieties 
in eruptive bosses and sheets. As far back as 1852, Delesse 
showed that the Ballon d'Alsace in the Vosges mountains 
consists of hornblendic granite in its central portion and its 
summit, but towards its peripheral portions passes into syenite 
and finally into diorite. More recently, in 1887, similar facts 
were demonstrated by Barrois in his brilliant account of the 
eruptive rocks in Brittany. The researches of Barrois have 


already become classic; generally speaking, they go to show 
that the mineralogical character of the stratified rocks as 
affecting the conduction of heat and the relative pressures 
between the bedded rocks and the intruded igneous rock- 
material, influenced the subsequent processes of consolidation 
in the latter, and determined the orientation of crystals and 
the modifications of structure. 

In many active and extinct volcanoes, it would appear that 
the character of the ejected rock-material gradually alters with 
each successive eruption, so that the first and the last products 
of eruption represent the extremes of a petrographical series. 
In the Rocky mountains, and in the Sierra Nevada, Baron von 
Richthofen (1868) recognised a definite sequence of propy- 
lite, andesite, trachyte, rhyolite, and basalt, and his observa- 
tions have since been confirmed by American geologists. The 
more recent works of Professor Broegger on the eruptive dis- 
trict of Southern Norway have extended the observations so 
ably initiated by Baron von Richthofen. Professor Broegger 
has given an admirable exposition of the eruptive rocks in 
that district with respect to their mineralogical, structural, 
and chemical constitution, their geological occurrence, their 
eruptive sequence, the division and differentiation of the 
original magma. 

In the year 1890, Professor Broegger contributed a paper 
to the Zeitschrift fur Krystallographie und Mine>alogie, in 
which he sub-divided the eruptive rocks in the neighbourhood 
of Christiania into two chief series, an older and a younger, 
the younger containing only basic intrusive rocks (diabases), 
the older comprising very different acid and basic rocks, which 
may be again sub-divided into five groups according to their 
mineralogical and chemical composition. All the products of 
this older group form a transitional series of rocks passing 
petrographically into one another, and closely related chemi- 
cally. They have clearly proceeded from an originally con- 
tinuous molten mass which has been segmented, and has 
undergone differentiation into several rock-types. The oldest 
members of the genetic series are basic, the youngest strongly 
acid. In the opinion of Broegger, the original magma was an 
aquo-igneous solution of silicates, and rich in soda. Towards 
the close of the Devonian epoch, the first fissure eruptions 
took place, the magma being still fairly basic, and these were 
succeeded from time to time by outbreaks of increasingly acid 


magma. The various magmas solidified sometimes under- 
ground as laccolites, sometimes as dykes, sometimes as super- 
ficial flows, and induced contact-metamorphism of diverse 
characters. Broegger could not determine any definite 
sequence in the separation of the component minerals, but 
was able to add many observations bearing upon this point. 

A later publication by the same author is entitled The 
Eruptive Rocks of the Christiania District, and comprises two 
volumes. The first, published in 1894, is devoted to the 
rocks of the Grorudite - Tinguaite series. Broegger thinks 
these take an intermediate position between deep-seated bosses 
and eruptive flows, and represent members of a connected 
series of protrusions from the same magma, which either 
solidified underground in massive form or occupied crust- 

The second volume, published in 1895, instituted a com- 
parison between the succession of eruptive rocks in the 
Christiania district and that in the eruptive district of Monzoni 
and Predazzo in South Tyrol. On the basis of his own 
observations in both districts, Broegger explains the famous 
Triassic monzonite, granite, and hypersthenite as deep-seated 
laccolitic expansions of the eruptive flows in the same neigh- 
bourhood (melaphyre, augite, porphyrite, and plagioclase 
porphyrite), and views them as a series of differentiations 
from an originally uniform magma, analogous with the differ- 
entiations presented in the Christiania district. 

From the foregoing pages it is apparent that Rosenbusch, 
Broegger, Iddings, Williams, and others are inclined to 
minimise the petrographical contrast between the so-called 
plutonic and volcanic rocks, and to recognise in underground 
and superficial occurrences of eruptive rock only different 
facies of the same magma, consolidated under different con- 
ditions. On the other hand, Zirkel (1893) strongly emphasised 
the differences between the granitic, deep-seated rocks and the 
porphyritic or glassy flows, and brings forward many objections 
to the laws enunciated by Rosenbusch regarding the succes- 
sive separation of minerals from fused masses. In general, 
petrographers may be said to be still actively investigating the 
ground-masses, in the study of which there are many problems 
awaiting solution. 

Microscopic researches have fully elucidated the composition 
and the origin of the sedimentary strata. There is no longer 


any difference of opinion regarding the derivation of the rock- 
material composing stratified deposits on the one hand from 
the fragmented and finely triturated products of surface denuda- 
tion or from the chemical activities of infiltrating water in the 
crust, and on the other, from the accumulation of organic de- 
posits. But the origin of gneisses and the crystalline schists is 
still shrouded in mystery; much is known, but far more remains 
to be discovered. These rocks used to be regarded as the 
fundamental rock-formation of the sedimentary succession ; 
the lowest member of the group being usually gneiss or coarsely 
foliated and banded granitic rock, and the uppermost usually 
phyllite or finely foliated lustrous, slaty rock. In the eighteenth 
century, three leading hypotheses were promulgated in explana- 
tion of the origin of these rocks. One theory (supported by 
Buffon, Breislak, and others) regarded the gneisses and the 
crystalline schists as the fundamental rocks of the earth's crust, 
the product of the first consolidation of molten rock material 
on the cooling surface of the earth ; the Wernerian theory 
represented them as the oldest chemical precipitates from the 
primaeval aqueous envelope of the earth, possessing a crystalline 
texture in virtue of the high temperature at the earth's surface 
in the primaeval epoch ; Hutton regarded them as normal 
sedimentary deposits, not necessarily of the primaeval epoch, 
which had been carried to greater depths in the crust after 
their deposition, and there been melted, metamorphosed, and 
rendered crystalline by the combined influence of the earth's 
internal heat and enormous crust-pressure. In his concep- 
tion of the relation of dynamic agencies to rock-deformation, 
Hutton was far ahead of his contemporaries, and the 
nineteenth century was well advanced before Darwin, Poulett- 
Scrope, Sharpe, and a few of the keenest observers began to 
apply the principle of dynamic agencies of deformation in the 
earth's crust. Beroldingen explained gneiss as regenerated 
granite. Although with certain modifications, each of these 
hypotheses claims supporters at the present day. 

In 1822 Ami Boue, in his geognostic description of Scotland, 
modified the Huttonian hypothesis in so far as he thought that 
in addition to subterranean heat and pressure, the action of 
vapours and gases had played a part in the metamorphosis of 
sedimentary deposits to crystalline rock. The Norwegian 
geologist. Keilhau, in the following year advanced his view 
that a foliated structure had been superinduced upon crystal- 


From a Photo by Walker & Cockcrcll, London, E.G., of a Painting 
by G. Richmond, R.A. 


line schists, in common with most of the older massive rocks, 
by the agency of water, without the aid either of pressure or of 
increased temperature. During the years 1826-28, Studer and 
Elie de Beaumont made the observation in the Swiss and 
Savoy Alps that gneiss and micaceous schists repose upon 
unaltered sedimentary strata, and that in certain crystalline 
schists fossils are present which prove them to belong to 
relatively young geological epochs. This discovery was a very 
great blow to the geologists who upheld the hypothesis of the 
Archaean or pre-Cambrian age of all gneisses and schists. 
Studer suggested some time later (1855) that the transforma- 
tion of these schists had proceeded not outward from the lower 
horizons to the upper, but possibly inward from younger and 
outer horizons of rock to deeper crust-levels. Hoffmann, who had 
in 1830 observed crystalline schists interbedded with conglomer- 
ates and coarse grits of the "transitional" series, advocated the 
view that the stratified grits and conglomerates represented un- 
altered patches, and the gneiss and schists represented altered 
portions of one and the same geological formation. 

Lyell accepted the Huttonian hypothesis in its essential 
features, and the wide circulation of his principles gave 
Mutton's teaching greater currency abroad. In addition to 
heat and pressure, Lyell thought electrical and other agencies 
might have combined to render the sedimentary structures 
semi-fluid, the rock material having then been re-arranged ; 
traces of organisms disappeared, but the bedding-planes for 
the most part persisted. Lyeli taught that gneiss and micaceous 
schist represented sandstones which had been altered by contact 
with eruptive rocks, argillaceous schists had been originally 
shales, and marble represented limestone that had been 
rendered crystalline. In accordance with the Huttonian 
doctrine that the high temperature had acted outward through 
the crust, the lowest schists and gneisses were said by Lyell 
to be those which had suffered the greatest degree of meta- 
morphism. At the same time, under certain circumstances 
comparatively young deposits might be metamorphosed, and it 
could by no means be assumed that all crystalline schists must 
belong to the fundamental or Archaean rocks. It was Sir 
Charles Lyell who gave to the group of gneiss and crystalline 
schists the name of " metamorphic " rock, and the name was 
rapidly adopted in the special literature of geology and in 

2 3 


Elie de Beaumont was the first to point out the contrast 
between widespread or normal metamorphism and the contact 
metamorphism which was limited to smaller zones of rock, and 
especially to the contiguous parts of eruptive and sedimentary 
rocks. Daubree afterwards applied the term of regional meta- 
morphism to distinguish these processes which had acted 
throughout vast regions of the crust and altered thick forma- 
tions of rock. 

One of the extreme Neptunists was Johann Fuchs, who 
explained the crystalline schists, gneiss, granitic and porphy- 
ritic rocks as segregation products from a watery or pasty 
material. The American geologist, Professor Dana, in 1843 
thought that the Huttonian doctrine did not attach sufficient 
importance to the agency of heated water in effecting rock- 
metamorphism. He compared gneiss with volcanic tuffs, and 
held the opinion that during invasions of granitic magma into 
the upper zones of the crust a granitic ash also escaped, and 
under the influence of superheated water became caked and 
cemented into the form of gneissose and schistose rocks. 
J. Bischof, in several papers published between the years 1847 
and 1854, agreed with Keilhau in assuming that the oldest 
sediments were for a long time supersaturated with water, and 
that chemical changes had slowly altered their constitution, 
converting argillaceous sediments first into clay-slate, and by 
continuance of the chemical processes into micaceous schists. 

Scheerer contributed in 1847 a suggestive paper on the 
origin of gneiss, in which he took the standpoint that it might 
be produced in various ways and from various rocks. He 
explained the gneiss of the Erz mountains as a rock that had 
been metamorphosed from sedimentary strata in situ, whereas 
the red gneiss during the time of its metamorphism had under- 
gone flow movements comparable to those of an eruptive 
magma. Again, in many cases gneiss was a fundamental 
Archaean rock representing a portion of the primaeval crust of 
the earth. Cotta also thought that most gneiss had formed 
part of the original crust, but he regarded the crystalline 
schists as the culminating result of a process of metamorphism 
undergone by all sedimentary rocks which had already been, 
or were now in process of being, covered by a thick mantle of 
younger deposits. The change, he thought, had been effected 
by heat and pressure, possibly in combination with water; and 
although the crystalline schists were in many places now ex- 


posed at the surface, they must have been subsequently elevated 
to that position, and the superincumbent rocks have been re- 
moved by denudation. Naumann supported the view that 
most gneiss and crystalline schists represented the oldest 
rock-sediments, but he agreed with Poulett-Scrope, Darwin, 
Fournet, Cotta, and others that many gneisses had been pro- 
duced by the deformation of eruptive rocks, and those might 
be of different ages. A similar standpoint was afterwards taken 
by Kjerulf and by Lehmann, the author of an excellent work 
(1884) on the ancient crystalline schists, with special refer- 
ence to the metamorphic rocks of the Erz mountains, Fichtel 
mountains, the mountains of Saxony and of the Bavarian and 
Bohemian frontiers. 

Delesse in 1861 declared himself an adherent of the meta- 
morphic doctrines, and ascribed rock-metamorphism to high 
temperature, water, pressure, and molecular movements. In his 
opinion, after the first crust formed on the cooled surface of the 
earth-magma, it was violently attacked by the action of the con- 
densed vapours and afforded material for a great accumulation 
of sediments. The metamorphism of these oldest sediments 
produced gneiss and the crystalline schists, and these could 
again become plastic and be transformed into plutonic rocks. 
Thus Delesse assumed the deep-seated granite series to have 
been produced by the re-melting and re-solidifying of meta- 
morphosed sediments. He was supported in this view by 
Daubree (1857). According to Daubree, the first-formed crust 
was saturated with the water of the primitive ocean, and the 
mineral constituents of gneiss and the oldest crystalline schists 
separated out from a pulpy, softened mass. The younger schists 
(chlorite schist, mica schist, phyllite) of the primaeval mountain- 
systems were thought by Daubree to be pre-Cambrian deposits 
metamorphosed by pressure and superheated water. The meta- 
morphism of the younger Alpine schists was also referred by 
Daubree to the same influences. 

Sterry Hunt similarly held that the crystalline schists re- 
presented the earliest chemical deposits. He thought they 
owed their planes of schistosity to the contemporaneous effect 
of intense heat combined with the action of water and pressure. 
He tried to elucidate the chemical processes of separation, 
to determine an order of deposition, and even to demon- 
strate that the eruptive rocks were also metamorphosed 
sediments, which after having been made plastic penetrated 


the sediments above and assumed the form of eruptive massive 

The microscopic examination of micaceous schist led Sorby 
(1856) to the assumption that it had originally been a shale 
and had been altered probably by means of water, a high 
temperature, and crust pressure. He regarded the foliated 
structure as a result of mechanical pressure. Hitchcock, in 
1861, also emphasised the action of mechanical strains. 

Sir William Logan's discovery, in 1867, of the thick series 
of gneisses and schists forming the floor of the sedimentary 
succession in Labrador and Canada, gave for a time additional 
support to the view of the Archaean age of all metamorphic 
rocks ; but every year stratigraphical researches were bringing 
new facts to light which could not harmonise with this simpler 
view of one primaeval epoch of formation for the crystalline 
foliated rocks. 

Zirkel, in 1866, made a complete resume of the literature on 
the subject of the metamorphic gneiss, and after a careful 
criticism of the facts and arguments, concluded that there is 
probably an original gneiss and a metamorphic gneiss. Water 
and the plastic magma have participated in the formation of 
the former ; it formed the first solid crust, and could, under 
certain circumstances, especially in the immediate vicinity of 
granite, partake of its eruptive character. Gneiss has either 
taken origin from shales and grits by contact metamorphism 
in the presence of heated water, or has arisen from the sub- 
terranean transformation of sedimentary strata by means of 
some simple processes of water-permeation, which have so far 
eluded discovery. Zirkel also explains the origin of granulite 
and the other crystalline schists upon principles of water- 
permeation, but he regards micaceous and chloritic schists 
and phyllites as metamorphosed sediments. 

Lossen initiated a new departure in the investigation of 
the metamorphic group, in so far as he succeeded in impressing 
geologists with the high value of accurate field investigations 
in assisting the solution of some of the intricate problems 
of metamorphism. During his examination of the Taunus 
mountains (1867), Lossen formed the opinion that most of 
the crystalline schists had originated as sedimentary strata 
containing a large amount of interstitial water, and had been 
cleaved and altered by the action of strong dynamic pressures 
during the mountain-making movements. Gneiss and mica 


schists had been, he thought, parts of the original granitic 
crust of consolidation, which had been similarly converted 
by pressure-metamorphism into banded, foliated, and cleaved 
rock-facies. Lessen subsequently examined and mapped the 
Harz mountains geologically, and found further confirmation 
of his theory of "dislocation metamorphism." He demon- 
strated in the Harz mountains that the same rocks which 
extended over wide regions as ordinary shaly sediments could 
be traced into a zone of crust disturbance, where they became 
crystalline and schistose, and were split by planes of cleavage 
superinduced upon the rock-strata at various angles with the 
planes of stratification. Although Lossen's work threw a new 
interest into phenomena of cleavage, the presence of cleavage- 
planes had long been known in certain rocks. As far back 
as the eighteenth century, Lasius and Voigt had drawn at- 
tention to the difference between the planes of stratification 
and planes of cleavage, but could not find any explanation. 
Sedgwick (1822 and 1835) suggested that the cleavage of rocks 
might be due to the action of polar forces along a definite 
direction, causing orientation of crystals in that direction. 
J. Phillips, in 1843, at a meeting of the British Association, 
pointed out the deformation of fossils in cleaved rocks, and 
thought cleavage was the result of a slow creep of the minute 
rock particles in a definite direction. An important observa- 
tion was made by the brothers Rogers, who showed, in 1837, 
that the cleavage-planes in the Alleghany mountains extended 
parallel with the main axis of upheaval of this mountain 
system, but in explanation they accepted Sedgwick's theory 
of polar attraction. 

Almost simultaneously, the action of lateral pressure was 
suggested by two observers: in 1846 by Baur, an overseer 
of mines in Eschweiler, who explained the cleavage of the 
greywackes in the Rhine Province by this means; and 
in 1847 by D. Sharpe. Sorby in 1853 made pressure 
experiments, and succeeded in reproducing cleavage arti- 
ficially in different kinds of rock. His results were sup- 
ported by the later experiments of Tyndall (1856) and 
Daubree (1861). 

When, therefore, Lessen from his actual field observations 
drew the important conclusion that crust disturbance had been 
the chief agent in effecting cleavage metamorphism, he was in 
a position to refer to the confirmatory evidence in favour of 


dynamic action which had been already afforded by experi- 
mental attempts. 

In 1887, a few months after Lossen's work on the Taunus 
had appeared, C. W. von Giimbel published his Geognostic 
Description of the Eastern Bavarian frontier Mountains. 
In it he tried to demonstrate that gneiss and crystalline 
schist represented the oldest sediment which had separated 
out under peculiar conditions from a magma impregnated 
with superheated water. Giimbel regarded the cleavage of 
gneiss and the crystalline schists in the Bavarian forest not 
as a subsequent development, but as true stratification, and 
compared the succession of the gneiss and schist series, as 
well as the gradual transitions and frequent alternations of 
the different varieties, with the characteristic appearances 
observed in a series of sedimentary deposits. He described 
the occurrence of certain massive rocks, such as granite, 
syenite, diorite, sometimes in regular alternation with the 
gneiss and schist, sometimes as intrusive bosses and dykes. 
Judging from the resemblance in the mineralogical composi- 
tion of all these massive rocks, Giimbel argued that the rock- 
material must in all cases have had a similar origin, and 
concluded that there was an underground magma constituted 
like the primitive earth, and from which either sedimentary 
schist and gneiss, or granitic bosses and layers, could develop. 

Justus Roth, who was one of the founders of the German 
Geological Society, was an ardent supporter of the view that 
all gneissose and schistose rocks represented the products of 
the first consolidation of the crust. In his work on General 
and Chemical Geology ', published in 1890, two years before 
his death, Roth gave an unfavourable criticism of all theories 
which advocated subsequent rock-deformation and meta- 
morphism. He contended that the compact structure of 
gneisses and schists, the absence of any amorphous or glassy 
ground-mass, together with the mineralogical composition, are 
features which indicate a plutonic, aquo-igneous origin. Their 
bent and cleaved character was attributed by him to the 
contraction of the earth and the consequent strains acting 
during the formation of the series. 

Many geologists were, however, finding in the field ample 
confirmation of Lossen's explanation of the mechanical defor- 
mation of rocks. The well-known writings of Heim and 
Baltzer on the Swiss Alps, of Renard on the rocks of the 


Ardennes, and of Lapworth on the north-west Highlands, 
revealed many new and highly interesting subjects of research 
in connection with dynamo-metamorphism. 

Johann Lehmann, in the work mentioned above (p. 355), 
accepted the views of Lessen, and demonstrated the effects 
of " dislocation metamorphism " from a large number of 
excellent illustrations of microscopic rock-sections. Accord- 
ing to Lehmann, the metamorphic rocks may be arranged in 
two groups. One comprises the various modifications of 
gneiss, granulite, felsite, and hornblendic schist which have 
originated as rock-material consolidated from molten magma, 
and have received their characteristic foliate structure from 
the action of pressures before solidification had been com- 
pleted. He advocated the plutonic origin of this group upon 
the assumption that there is in the crust a corresponding 
rock-magma, the source of the deep-seated eruptive rocks, 
granite, syenite, diorite, gabbro, and that these rocks are con- 
nected with the gneiss group by a complete series of transitional 

The other group comprises the remaining crystalline schists, 
gneissic schist, micaceous schist, chloritic schist, talcose schist, 
phyllites, etc. These have been produced by "dislocation 
metamorphism " carried out in very high degrees. In the 
case of gneissic schist the original rock-material, while under- 
going the processes of metamorphism, has been invaded 
by, or impregnated with, granitic injections, but the series 
of typical schists have been metamorphosed without any 
injection of foreign magma. The original character of the 
rock-material is, according to Lehmann, not always demon- 
strable, but he thinks it abundantly evident that the meta- 
morphic series is intimately associated in the field both with 
fragmental or clastic deposits and with rocks of igneous 
origin. Lehmann insisted that it was erroneous to attribute 
the metamorphic schists to a definite, pre-Cambrian geological 
epoch ; it was in his opinion far more probable that they 
belonged to the different epochs during which extensive 
mountain-movements had been in progress. Professor Barrois 
in 1884 likewise showed that the schists and gneisses in 
Brittany, which had been regarded as pre-Cambrian, really 
represented metamorphosed sedimentary deposits belonging to 
various Palaeozoic epochs. 

The involved stratigraphical problem presented by the 


extensive district of regional metamorphism in the north-west 
of Scotland had meantime been brilliantly elucidated by 
Professor Lapworth. Messrs. Peach and Home, together with 
other members of the Geological Survey, were continuing the 
work of mapping and research in the new light that had been 
thrown on the problem by Lapworth's demonstration of the 
great crust-movements of overthrust, and the associated meta- 
morphism of portions of the Cambro-Silurian deposits. It 
was securely determined in that district of regional metamor- 
phism that there was fundamental gneiss at the base of the 
whole sedimentary succession, and also metamorphic gneiss 
representing sedimentary rocks of the oldest Palaeozoic epochs 
which had been locally altered during the gigantic crust-move- 
ments. The altered and unaltered deposits dovetailed into 
one another with complicated stratigraphical relations. 

The conclusive results of the work done in the north-west 
Highlands of Scotland were of the highest importance for the 
general questions in dispute regarding the causes and processes 
of metamorphism. In more recent years, Mr. Barrow has 
shown the presence of eruptive bosses of gneiss as well as of 
granite, and has traced numerous veins of pegmatite passing 
from these bosses into the group of crystalline schists. 

The last fifteen years of the nineteenth century witnessed 
very great advances in our knowledge of rock-deformation 
and metamorphism. It has been found that there is no 
geological epoch whose sedimentary deposits have been 
wholly safeguarded from metamorphic changes, and as this 
broad fact has come to be realised, it has proved most un- 
settling and has necessitated a revision of the stratigraphy of 
many districts in the light of the new possibilities. The 
newer researches scarcely recognise any theory ; they are 
directed rather to the empirical method of obtaining all possible 
information regarding microscopic and field evidences of the 
passage from metamorphic to igneous rocks, and from meta- 
morphic to sedimentary rocks. The present views held by 
the leading German petrographers, Rosenbusch and Zirkel, 
may be in conclusion shortly indicated, as they will give a 
fair representation of the existing progressive and conservative 
tendencies regarding the difficult questions of pressure-meta- 

Rosenbusch has strongly advocated the origin of the crystal- 
line schists through dynamo -metamorphic agencies. In a 


paper Written in 1889 he does not confine the metamorphic 
action of mountain-movements to sedimentary formations, but 
in common with Lehmann he regards gneiss, hornblendic 
schist, and other crystalline schists as eruptive rocks (granite, 
syenite, diorite) in which planes of schistosity have been 
developed under the influences of pressure and stretching. 
Rosenbusch does not believe it possible that the fundamental 
gneisses and schists could have originated as chemical precipi- 
tates from a primaeval ocean, or any primaeval mixture of 
rock-material and superheated water. As he further points 
out, the idea has been exploded that schistosity is a feature 
peculiar to Archaean rocks, it may indeed be possessed by 
young-Tertiary rocks. From the general distribution and 
stratigraphical position of the "fundamental" series, Rosen- 
busch concludes that it represents in its deeper horizons the 
first consolidated crust. He thinks the agreement in the 
mineralogical composition, as well as the interleaving of the 
Archaean gneisses and schists with the oldest eruptive rocks, 
would seem to indicate that the Archsean foliated rocks have 
at least in part originated from the same magma as deep-seated 
plutonic rocks. But whereas in the case of the granite-grained 
bosses of rock there is internal evidence that the minerals had 
separated from the magma in a definite order according to 
chemical laws, this is quite lacking in the gneissose and 
schistose rocks, which rather indicate that consolidation had 
been controlled by mechanical pressure. 

In chemical respects the crystalline schists agree sometimes 
with massive eruptive rocks, sometimes with sedimentary 
rocks, and in all probability they have originated from various 
rocks, from deep-seated and eruptive masses, from intrusive 
and superficial eruptive flows, from eruptive tuffs, and from 
all kinds of stratified deposits. According to Rosenbusch, 
dynamo-metamorphism is the active principle that produces 
the banded and finely foliated forms of rock-structure. 

In his Elements of Petrology (1898) Rosenbusch defines the 
crystalline schists as "eruptive or sedimentary rocks which have 
been geologically transformed through the essential co-opera- 
tion of geo-dynamic phenomena." He distinguishes the 
" fundamental " series as an independent primaeval formation, 
and describes the younger schists as local facies of different 
rock-varieties and not confined to any geological epoch. 

Credner and Zirkel take exception to these views in certain 


points. They admit the conversion of certain granites to 
gneissoid rocks, but do not agree that dynamo-metamorphism 
has had any part in the origin of the true Archaean gneisses 
and schists. Credner finds it difficult to understand how such 
a uniform succession as is presented by the fundamental 
crystalline rocks in the ancient mountain-systems could have 
been the product of variable and accidental processes of 
crushing and permeation by water. 

Zirkel draws attention to the fact that the typical funda-, 
mental rocks and even the younger schists in many districts 
show only very slight traces of mountain-pressure, and on the 
other hand sedimentary rocks have often suffered gigantic 
tectonic disturbances and pressures, and yet have not been 
much changed in their original constitution. The petrographi- 
cal researches of Professor Salomon have during the last few 
years attracted considerable attention. Professor Salomon has ! 
investigated the contact phenomena associated with deep- | 
seated eruptive rocks in the Alps, more especially in the 
Adamello group, and has shown that different kinds of rocks 
have throughout long distances been altered by contact meta- 
morphism into crystalline schists. On the basis of his ob- 
servations in the Adamello, in the Cima d'Asta, and Predazzo 
districts, and in other parts of the Alps, Salomon has inferred , 
that the granite-grained bosses of the Tyrol Central Alps are 
not, as Broegger concluded, of Triassic age, but were intruded 
in the Tertiary epoch. The magmas solidified in the form of 
laccolites and batholites, and as the form of the intruded 
material frequently varied in its relation to the crystalline 
schists during its cooling and contraction, Professor Salomon 
thinks it possible that the latest Alpine upheaval may have 
been induced by such variations and the consequent disturb- 
ances of crust equilibrium. 

Although the hypothesis of dynamo-metamorphism has now 
very numerous adherents, many questions regarding the origin 
of the fundamental and the younger schistose rocks have yet 
to be solved before the principles of metamorphism can be 
securely defined, and as the subject is still under discussion, it 
is not well suited for historical interpretation. 



AFTER William Smith, Alexandra Brongniart, and Cuvier had 
disclosed to geologists the significance that attached to fossils 
as organic relics characteristic of successive geological epochs, 
some of the most enlightened scientific men of the day shared 
the increased interest in the study of fossils, and, greatly to the 
advantage of this branch of research, directed their genius to 
the examination, identification, and classification of fossils in 
the light of comparison with the existing plant and animal 
world. Blumenbach, Cuvier, Lamarck, Schlotheim, and others 
applied the scientific methods of Zoology, Comparative Ana- 
tomy, and Botany to the investigation of the remains of fossil 
organisms. A knowledge of fossil remains was no longer 
viewed as the hobby of a few dilettantes, but at the chief seats 
of learning was elevated to the rank of an independent mental 
discipline in the scientific curriculum. The new science was 
given the name of " Palaeontology " almost simultaneously by 
two eminent authors, Ducrotay de Blainville and Fischer von 
Waldheim (1834), and the name was rapidly adopted in 
France and England, although in Germany the older terms 
" Petrefaktenkunde " and " Petrefaktologie " held their place 
for many decades. 

Two directions were from the first apparent in palseontologi- 
cal research a stratigraphical and a biological. Stratigraphers 
wished from palaeontology mainly confirmation regarding the 
true order or relative age of zones of rock deposits in the field. 
Biologists had, theoretically at least, the more genuine interest 
in fossil organisms as individual forms of life ; for the biologist 
or student of existing life the supreme value of palaeontology 
was the evidence it might bring towards the solution of the 
problems of the genesis and evolution of living forms, deter- 
mination of species and genera, variation of types in its rela- 
tion to climatic conditions, distribution of types in respect of 



geographical provinces, and many other fascinating subjects 
for scientific thought and investigation. 

The stratigraphical aspect of palaeontology is, however, the 
chief care of the geologist. He has to unearth the fossils, 
note their environment, trace the particular fossiliferous bed 
of deposit in its farther extension, and observe whether the 
fossils are only of sporadic occurrence in that horizon of 
rock, or are distributed throughout wide areas ; again, whether, 
the fossils are less frequent at that horizon than at some others 
horizon a little above or a little below in the rock-succession,; 
or if the fossils are so very abundant at that horizon as toj 
represent leading fossil types, characteristic of that geological' 
horizon or zone of rock. 

Many writers on fossil organisms have treated them merely 1 
as a means of identifying the age of the rocks, and have! 
neglected the biological features. More general interest is com- 
manded by descriptions of complete faunas and floras belonging 
to a definite epoch in the geological history of the earth. 
Although monographs of this character are, in the first; 
instance, of stratigraphical value, the data which they bring i 
forward are of use in determining the development of organic j 

The first attempt at a Chronological Succession of fossil I 
organisms is to be found in H. G. Bronn's 1 Lethaa Geognostica 
(1835-38). This work is a masterpiece of scholarship; it sum- 

1 Heinrich Georg Bronn, born on the 3rd March 1800, at Ziegelhausen, 
near Heidelberg, the son of a forester, studied in Heidelberg, and became 
a university tutor there in 1821 ; in 1828 Professor of Zoology and Tech- 
nology. Between 1824 and 1827 he travelled in Upper Italy and Southern 
France for the sake of palseontological and geological studies. From 
1830-62 he was one of the co-editors of the Jahrbuch fur Mineralogie, 
Geognosie, und Pa'atontologie. His chief works, the Lethcea Geognostica, 
the Handbook of Natural History, the Investigation into the Developmental 
Laws of Organised Nature, brought him the reputation of being the most 
distinguished palaeontologist in Germany. His difficulty of hearing was 
a decided drawback to his teaching powers. Wissmann, Lommel, G. 
Schweinfurth, and Zittel are among his grateful scholars. Bronn died in 
1862 in Heidelberg, from lung disease. The first volume of the Lethcpa 
Geognostica appeared in 1835, and was so widely circulated that a second 
edition of it was called for before the publication of the second volume 
the latter was published in 1838. A third edition in three volumes, and 
with 124 plates, was published between 1851 and 1856, with the co-opera- 
tion of Ferdinand Roemer, who had undertaken the preparation of the 
Palaeo-Lethsea or Carboniferous Period. A fourth edition was begun in 
1876 by Roemer, and is at present being continued by Professor Freeh. 


marises all that was previously known about stratigraphy and 
palaeontology. The most important fossil types of all the geo- 
logical formations are shown on the forty-seven folio plates, 
and the text gives careful descriptions of the fossils and their 

The Lethcza Geognostica was followed in 1848-49 by an 
Index Palceontologica, in which Bronn was assisted by Goeppert 
and H. von Meyer. Both these works exerted a great 
influence on the development of palaeontology, and were for 
several decades the chief books of reference for all the more 
comprehensive palaeontological works. Several other large 
works were published in the early part of the nineteenth cen- 
tury; among others, the Mineral Conchology of Great Britain, 
by the Sowerbys, between 1812 and 1845 (ante, p. 131); 
the splendid series of plates, Petrefacta Germanics, by 
Goldfuss 1 and Count Miinster ; the Pal'eontologie Fran$aise, 
by Alcide d'Orbigny (1840-55). Goldfuss and Miinster 2 
intended to produce an illustrative work of all the 
invertebrate fossils occurring in Germany, but apparently 
found the scheme too extensive, and concluded the work after 
the sponges, corals, crinoids, echinids, and a part of the fossil 
mollusca had been accomplished. D'Orbigny also gave up 
his similar scheme of an exhaustive illustrated account of all 
the fossil Invertebrates in France; he brought to completion 
monographs of the Jurassic and Cretaceous Cephalopods, 
Gastropods, the Cretaceous Lamellibranchs, Brachiopods, and 
Bryozoa, and certain groups of the Cretaceous Echinids. 

In the first volume of the Elementary Course of Palaeontology 
and Stratigraphical Geology (1849), D'Orbigny gave a short 
systematic summary of fossil organisms. The Prodrome of 
Palaeontology is a list of the fossil Mollusca, Sponges, and 
Foraminifera arranged according to the geological epochs, but 
the list is much less complete than Bronn's Palceontological 

1 Georg August Goldfuss, born 1782 at Thurnau, near Bayreuth ; 
studied in Erlangen, graduated there in 1804, in 1818 was made Professor 
of Zoology in Erlangen, but was soon after called to Bonn University as 
Professor of Zoology and Mineralogy; died 1848, in Bonn. 

' 2 Count George Miinster, born 1776 of a Hanoverian family, held office 
as a Bavarian Chamberlain, and lived in Bayreuth, where he died in 1844. 
His famous collection of fossils was procured by the Bavarian State and 
removed to Munich, where it formed the nucleus of the present Pabeonto- 
logical Museum. 


The Palseontographical Society was established in London 
in the year 1847 f r tne purpose of illustrating and describing 
the whole of the British Fossil Species. The work it has 
accomplished is most praiseworthy. Each year has seen the 
publication of a volume containing monographs by the first 
specialists. Among the contributors have been Richard 
Owen, H. Milne-Edwards, E. Forbes, T. Davidson, H. 
Woodward, Ray Lankester, Traquair, Nicholson, Lapworth, 
Hinde, and many others whose names have a world-wide 
repute in connection with their special researches of animal 
groups. The publications of the Palseontographical Society 
undoubtedly take the first place in the literature of fossils, 
although the monographs are confined to British fossils. A 
more universal character is presented by the volumes of 
the Palceontographica, a periodical which was commenced in 
1846 by W. Dunker and H. von Meyer. For the last three 
decades the Pal&ontographica has been conducted by K. von 
Zittel, and now numbers forty-six volumes. Similar palseonto- 
graphical journals have been instituted in Austria-Hungary, 
France, and Italy. 

Some of the more important works which treat fossils rather 
from their biological than their stratigraphical standpoint are 
Buckland's Mineralogy and Geology (1836), G. A. Mantell's 
Medals of Creation (1844), and the excellent Trait'e elementaire 
de Paleontologie^ published by F. J. Pictet at Paris (1844-46). 
Buckland's widely-circulated book was translated into German 
by the elder Agassiz. In the short geological introduction, 
Buckland impresses upon the reader the confirmation given 
by the geological record to the words of Holy Writ ; then 
follows an attractively written account of fossil organisms, in 
the course of which frequent reference is made to the modes 
of life of the various animal groups, and to the relations 
subsisting between the fossil and living representatives of 
organised existences. 

Pictet 1 treated palaeontology as an essential part of the studies 

1 Frar^ois Jules Pictet, born on the 27th September 1809, scion of an 
aristocratic family in Geneva. He studied Law and Science at the Geneva 
Academy, and went in 1830 to Paris, where he associated much with 
Cuvier, Geoffroy Saint-Hilaire, Blainville, and Audouin. In 1833 he 
returned to Geneva, interested himself chiefly in entomology and Compara- 
tive Anatomy, and married Miss de la Rive, a grand-daughter of Necker 
de Saussure. In 1835, Pictet was appointed Professor of Zoology at the 
Academy, but retired in 1859, in order to devote himself wholly to his 


of Zoology, Comparative Anatomy, and Botany. He confined 
himself in his treatise to fossil animals, and adhered to 
a strict systematic order throughout his work, constantly 
keeping in view the characteristics of the corresponding living 
forms. At the same time, the geological occurrence of the 
fossils is nowhere omitted. In his treatment of the Mollusca 
and Echinoderms, Pictet agrees as a rule with D'Orbigny's 
views; in classifying the Vertebrates he relies chiefly upon the 
works of Cuvier and Agassiz. Pictet's work was taken as a 
model for a number of text-books which rapidly made their 
appearance. The Principles of Paleontology, by H. B. Geinitz 
(1846), keeps closely to Pictet's order and treatment of the 
subject; C. G. Giebel's Paleontology (1852) is merely a short 
summary, his unfinished Fauna of the Past (1847-56) is a 
diligently compiled enumeration of all known Vertebrates, 
Cephalopods, and Arthropods. A large number of new 
observations and illustrations are contained in F. A. 
Quenstedt's well-known account of fossils, Petrefaktenkunde 
(Tubingen, 1852). The work had passed through three 
editions in 1885, and for more than three decades was the 
chief handbook of palaeontology used by the German students. 
Quenstedt's larger work, Petrefaktenkunde Deutschlands^ with 
two hundred and eighteen plates, was published at intervals 
between 1846 and 1878. As a collective book of reference on 
the Vertebrate fossils found in Germany, it is indispensable in 
palaeontological libraries. Sir Richard Owen's Paleontology 
(1860) provides an excellent general survey of the Vertebrate 
animals, but the Invertebrates are insufficiently treated. 

The systematic direction of palaeontology was until 1860 
under the influence of Cuvier's theory of the invariability of 
species. Lamarck's bold hypotheses regarding the transmuta- 
tion and descent of organic forms remained almost neglected 
by palaeontologists, although H. G. Bronn, Quenstedt, and a 
few others had no belief in the fixed invariability of species, 
nor in the sharp distinctions drawn between successive periods 
of creation supposed to have been separated from one another 

palceontological labours, and the direction of the Natural History Museum. 
Between 1866 and 1868 he became Rector of the Geneva Academy, and 
was at the same time a member of the Council of Education for the 
Zurich Polytechnic School ; he also took an active part in political life, 
was a member of the Grand Council of Geneva, a,nd of the National 
Council in Bern. He died on the I5th March 1872. 


by great earth -cataclysms. Otherwise palaeontological re- 
search between 1820 and 1860 made remarkable advances. 
Innumerable new forms were brought to light by zealous strati- 
graphers during their field surveys ; while the museums were 
rapidly extending their collections, and affording ready oppor- 
tunities to the younger minds of assimilating the broad facts 
and tendencies of palaeontological investigations. 

Schlotheim had in 1804 laid the ground-work of a knowledge 
of fossil plants, and Count von Sternberg l worthily continued 
these pioneer labours. His chief work, Attempt at a Geognostic 
Botanic Representation of the Flora of the Past (1820-32), 
describes two hundred fossil species of plants, and is illustrated 
by sixty splendid folio plates. Sternberg tried to insert the 
fossil species into the botanical system of existing floras, 
applied names correspondingly to the fossil species, and dis- 
carded the old names under which the fossil forms had been i 
known. He accomplished much for the proper botanical sig- 
nificance of fossil floras, and paved the way for a scientific 
treatment of palaeophytology. 

A year after the appearance of the first part of Sternberg's 
work, Adolphe Brongniart 2 began his celebrated studies in 
fossil plants. 

Like Sternberg, Brongniart also consistently carried out the 
examination and description of fossil plants strictly on lines of 
comparison with living plant-forms, and he arrived at similar 
results. Brongniart had at his disposal much more extensive 
material of observation than his German contemporary. His 
first Treatise on the Classification and Distribution of fossil 
Plants is therefore the most complete and most scientific 
summary of all the fossil plants known before the year of 
its publication, 1822. A large, richly illustrated work, whose 
contents were made known in a preliminary Prodrome, was 
intended to form a fuller supplement to the earlier treatise, 
but unfortunately was never completed, and contains only the 

1 Kaspar Maria, Count von Sternberg, born 6th January 1761 at 
Serowitz (Bohemia), belonged to an old family, was president of the 
Bohemian National Museum, to which he bequeathed his library and 
collections; died 2Oth December 1838. 

2 Adolphe Theodore Brongniart, born 1801 in Paris, the son of the 
famous geologist, Alexandre Brongniart, studied medicine, but occupied 
himself chiefly with botany; was in 1833 appointed Professor of Botany 
at the Botanical Garden, in 1852 General Inspector of the University of 
France; died on the I9th February 1876, in Paris. 


monographic description of a large part of the Cryptogams. 
Nevertheless, the unfinished work created a model of the best 
methods of palaeophytological investigation. 

Although an adherent of Cuvier's theory, Brongniart pointed 
out the gradual development of the floras in successive geo- 
logical periods, and thought that the atmosphere, which had been 
in the earliest epochs warm and moist and supersaturated with 
carbonic acid gas, became purer and colder in course of time, 
and less suitable for the lavish development of vascular crypto- 
gams. According to Brongniart, plant-life began on small 
islands in the primaeval ocean ; these islands afterwards 
united to continents, and the vegetation that spread over 
them always progressed towards more perfect types, and 
approached more nearly to the flora of the present epoch. 
He thought that the great changes in the floras and faunas of 
past ages had been effected contemporaneously by stupendous 

Peculiar results were obtained by J. Lindley and W. Hutton 
in their study of the fossil flora of Great Britain. Their un- 
finished work, consisting of three octavo volumes, was published 
between 1831 and 1837, a d contains good descriptions and 
illustrations of most of the Carboniferous types. Both authors 
contest the existence of tree-ferns in the Carboniferous forma- 
tion, doubt the relationship of the Calamites to the Equisetacese, 
and are of opinion that the Carboniferous flora included not 
only Conifers, but Cacti, Euphorbias, and other dicotyledons. 
They altogether deny a progressive development of the fossil 

Brongniart and his predecessors had identified the fossil 
forms exclusively from microscopic features : the finer 
structures came little into consideration, A new field of 
research was opened by several papers which gave an account 
of the microscopic structure of wood. One of the earliest was 
an essay by Sprengel (1828) on the silicified stems of trees 
(Psaronites). This was followed in 1831 by Witham's treatise 
on the structure of fossil and recent woods, and in 1832 by 
Cotta's richly illustrated work on the tree-ferns (various species 
of Psaronius) from the Red Underlyer or Lower Dyassic rocks of 
Saxony. An important work was published by August Corda 
between the years 1838 and 1842 on the comparative structure 
of fossil and recent stems. The illustrations of this work were 
admirably drawn by the author himself. The memoir in 1839 



by Brongniart on the structure of Lepidodendron, Sigillaria, 
and Stigmaria is still treasured as a model of accurate methods 
of observation. His chronological summary of the periods of 
vegetation, and of the different floras according to their succes- 
sive appearance on the face of the earth, is the first and most 
complete compilation of the fossil floras. 

The numerous and valuable phytological works of H. R. 
Goeppert 1 extend over half a century, from 1834 to 1884. 
No other scientific man has been such a prolific writer on fossil 
plants, and there is scarcely any domain in fossil botany which 
has not come under Goeppert's special investigations. His 
monographs on the genera of fossil plants (1841-46), on the 
Tertiary floras of Silesia and Java, on fossil ferns (1836), and 
conifers (1850), as well as his excellent researches on the micro- 
scopic structure of fossil woods, coal and brown-coal, are 
among the best contributions that have been made to the 
knowledge of fossil vegetations. 

In comparison with the flora of the older geological periods 
that of the Tertiary period was for a long time little investigated, 
but about the middle of the nineteenth century several works 
were devoted to this period. Franz Unger, Professor of 
Botany and Zoology in Graz, published between 1841 and 
1847 the Chloris Protogcea^ in which more than one hundred 
and twenty new species of Tertiary plants are described, illus- 
trated, and classified under genera still existing. 

In a second work on the flora of Sotzka, a great number 
of fossil Tertiary plants are represented on forty-seven folio 
plates, and the Sylloge plantar urn fossilium (1860-66) con- 
tains descriptions and illustrations of three hundred and 
twenty-seven Tertiary species. The Synopsis of fossil plants 
(1845), of which a second edition appeared in 1855, provides a 
summary of the whole of phyto-palaeontological material, and it 
was accompanied by the well-known series of coloured plates 
which Unger designed to convey an impression of the charac- 
teristic appearance presented by the successive floras in the 
world's history. 

Alexander Braun (1845) made a special study of the remains 
of Tertiary plants found near Oeningen in Switzerland. The 

1 Heinrich Robert Goeppert, born 1800, at Sprottau in Lower Silesia, 
Doctor of Medicine, was originally a pharmaceutical chemist; in 1827 
University Tutor, in 1831 Professor of Botany in Breslau ; died i8th May 


Ziirich botanist, Oswald Heer, 1 has made his name famous by 
the admirable comparative researches which he carried out on 
the flora of Oeningen and other North Alpine localities. His 
first pal^eontological works reach as far back as 1847. His 
masterpiece appeared between 1855 and 1859, the Tertiary 
Flora of Switzerland^ in two volumes, wherein no less than 
nine hundred species, for the most part new species, are 
described; one hundred and fifty-five plates illustrated the 

His scholarly mind and wide knowledge of his subject 
enabled Heer to reconstruct in the ablest manner the different 
floras of the Tertiary epoch, to compare them with those of 
other Tertiary districts and of the present, and to discover by 
this means what had been the temperature and other climatic 
conditions during the growth of the successive Tertiary floras. 
The results of these important researches were afterwards 
published in the form of a popular scientific work, The 
Primeval World of Switzerland (1864), and roused great 
interest in a wide circle of readers. Another fundamental 
work by O. Heer treats the fossil flora of the Arctic regions. 
It consists of several independent treatises written in different 
languages; the whole work comprises seven quarto volumes, 
which were published between 1869 and 1884. The Flora 
Arctica forms not only an important contribution to the 
systematic knowledge of fossil floras, but is a work of the 
highest geological value on account of its inferences regarding 
the earlier climates of Arctic regions. 

Heer advocates the view of a gradual approach of fossil 
floras to living creation, and a progressive differentiation and 
perfecting of all organised forms. He thinks the innate 
tendency of the organic world towards higher evolution was 
implanted in it by the Creator, and that evolution takes place 
in accordance with immutable laws. In his opinion, the 
variations of species and genera were not accomplished, as 
Darwin supposes, by means of slow modifications in the 

1 Oswald Heer, born 3ist August 1809, at Niederutzwyl in Canton St. 
Gallen, the son of the Protestant pastor, studied Theology in Halle, and 
graduated, but in 1834 accepted a university tutorship at Zurich University ; 
in 1852 was appointed Professor in the same University, and afterwards held 
also a Professorship in the Polytechnic Academy of Zurich. In 1852 he 
spent eight months in Madeira on account of lung weakness; in 1870 the 
old weakness broke out afresh, and on 27th September 1883 he died in 


course of countless generations, but at definite periods of 
creation, by means of a more or less complete re-modelling of 
the previously existing species in the plant and animal 

The numerous, and in some cases beautifully illustrated, 
works of Abramo Massalongo (between 1850 and 1861) 
elucidate the Tertiary floras of upper and middle Italy. 
Another voluminous writer on Tertiary floras was Baron von 
Ettingshausen. 1 His first works discuss the Tertiary plants 
of the Vienna basin and the fossil Proteaceae. 

A method of securing a natural impression of leaves was 
about this time discovered in the Government Printing Office 
at Vienna, and Ettingshausen immediately had the method 
adapted to facilitate scientific researches of recent and fossil 
types of venation. In a memoir published in 1854, 
Ettingshausen showed the importance of leaf-venation for the 
systematic identification of isolated fossil leaves, and suggested 
a special terminology for the nervation of leaves. His large 
work is a handsomely-prepared account of Austrian plants in 
six volumes, Physio typia Plantarum Austriacarum, illustrated 
by natural impressions of the leaves. Pokorny collaborated 
with Ettingshausen in the preparation of this work, which was 
exhibited at the Paris Exhibition in the year 1867. Several 
independent monographs by Ettingshausen succeeded this 
work, and methods which he initiated have added very greatly 
to the security with which fossil leaves may be identified. 
Ettingshausen followed Heer in constantly making a com- 
parison between recent and fossil forms, but, unlike Heer, he 
was an enthusiastic believer in the Darwinian theory of 

Meanwhile the knowledge of Carboniferous floras was being 
from time to time enriched. W. C. Williamson contributed 
several works (1851-68) on the Carboniferous flora of Great 
Britain ; that of North America was being carefully examined 
by Sir William Dawson and Leo Lesquereux. 

The first complete enumeration of palaeophytological material 

1 Constantin Freiherr von Ettingshausen, born 1862 in Vienna, the son 
of the physicist, Andreas von Ettingshausen, studied in Kremsmiinster and 
Vienna ; worked as a voluntary assistant on the Imperial Geological 
Survey; in 1854 was chosen Professor at the Emperor Joseph Academy, 
and in 1871 Professor of Botany at Graz University ; he died at Graz 
in 1897. 


is found in the Traite de Paleontologie vegetale (Paris, 
1869-74), by Philipp Schimper, who was Director of the 
Museum in Strasburg, and a Professor in the University. 
Schimper handled the material essentially from a botanical 
standpoint, but was also an admirable exponent of the geo- 
logical relations and significance of fossil plants. 

August Schenk, for a long time (1868-91) Professor of 
Botany in Leipzig, exerted a very great influence on the 
advance of palseophytology in Germany. His detailed works 
were devoted to an investigation of the flora of the French 
Keuper, and more especially to the plant forms from the passage- 
beds between the Keuper and Lias. These appeared before 
1868, while Schenk was still Professor of Botany in Wiirzburg. 
After his removal to Leipzig he came more into touch with 
Berlin influences, and he undertook the investigation of the 
large collection of fossil floras which had been brought from 
China by Baron von Richthofen and Count Szechenyi. Other 
materials examined by him were the silicified woods from the 
Nubian sandstones, fossil wood from Cairo, the plant remains 
from the Muschelkalk of Recoaro and from the Weald forma- 
tion of England. 

While all these were of the nature of special researches, a 
work of more general interest is Schenk's systematic treatment 
of the fossil plants in ZittePs Handbook of Palaeontology. After 
the death of Schimper, who had only completed the crypto- 
gams and cycads, Schenk undertook in 1881 the continua- 
tion of this work. By means of the critical method which he 
carried out uniformly throughout his classification of flowering 
plants in Zittel's handbook, and from which the works of the 
highest authorities, such as Unger, Heer, Von Ettingshausen, 
and Saporta, were not spared, Schenk practically initiated a 
reform in palaeophytology. He showed how many of the fossil 
genera and species had been based on insufficient grounds of 
distinction, and how often miserably preserved fossil remains, 
whose identification was impossible, had been used for the 
erection of new genera or made the basis of some wonderful 
new hypothesis. Many of the special papers on fossil plants 
had been contributed by authors with insufficient botanical 
training, and were in consequence an untrustworthy foundation 
for any inductive reasoning regarding the past periods of 
vegetation and their climatic conditions. 

Schenk was also very dubious about the value of Ettings- 


hausen's application of leaf-nervation as a means of identifying 
fossil leaves, since the course of the leading bundles sometimes 
showed the greatest variability within smaller and larger groups, 
sometimes on the contrary showed scarcely any differences. 
The shapes of the leaves could, in his opinion, at the most 
be used only as a specific feature of distinction. To these 
inherent difficulties in systematic botany was added the fact 
that in the case of the fossil types it was quite exceptional to 
find leaves, flowers, and fruits embedded in the same localities 
in such a way as to demonstrate their original association with 
one another ; and the want of caution displayed by many 
inquirers had created a mass of palaeophytological literature 
which for scientific purposes was little more than useless ballast 
to be discarded. 

Schenk fearlessly and patiently carried out the task of sifting 
the valuable results from the worthless, and by his precise 
and comprehensive knowledge of living forms he brought the 
scattered information regarding extinct forms into line with the 
most recent aspects of botanical science ; his classificatory 
treatment of fossil floras is now adopted by the best 

Schenk was a warm supporter of Darwin's theory of 
descent. His remarks on the genealogical relationships of the 
different fossil groups of plants and the modifications and 
variations of the ancient floras are of unusual interest. No 
less suggestive are his inferences regarding the climates of 
former ages and the general character of the vegetation. 
Schenk's views on such subjects frequently differ from those 
of Ettingshausen and Heer. 

The Marquis of Saporta (1823-95), the head of a noble 
family, devoted all his leisure to the study of botany, and in 
1860 began to interest himself especially in fossil plants. His 
writings are among the most valuable descriptions that have 
been given of fossil floras. They deal largely with the rich 
Tertiary floras of Southern France. He described the famous 
flora in the gypsum beds of Aix, in the Lower Eocene travertine 
deposits of Sezanne (1865), in the marls of Gelinden (1873), 
and in the Pliocene deposits of Meximieux (1876). Saporta 
was also the author of several successful popular works, 1 which 

1 The most widely circulated of Saporta's books are The World of Plants 
before the Appearance of Man (Paris, 1881 and 1885) and The Pahzonto- 
logical Origin of Trees (Paris, 1888). 


elucidate the developmental phases of the floras of past time 
in the sense of the theory of evolution. 

In his Cours de la Botanique fossile (Paris, 1881-85), M. B. 
Renault describes the fossil cycads, cordaites, sigillarias, lepido- 
dendrons, stigmarias, ferns, and conifers. His classification 
adheres closely to the systematic arrangement of living plants. 
The same plant-groups, together with thallophytes, mosses, 
calamarias, and equisetes, are ably described in a German 
work which appeared about the same time, Einkihing in 
die Palaophytologie^ by Count von Solms-Laubach (Leipzig, 

Upon the whole, botanists have always taken a more im- 
portant part than geologists in the advance of palaeophytology, 
and in recent years the purely botanical treatment has become 
even more predominant. The severe strictures passed by 
Schenk on the uncritical palaeontological papers that appeared 
so numerously in the middle of the last century have had their 
influence ; now the author of a paper on any department of 
palaeophytology is expected to have a sound knowledge of 
systematic botany. 

It cannot be said that palaeozoology has yet arrived at this 
desirable standpoint. Just as palaeophytology has come to be 
regarded and treated scientifically as a branch of botany in the 
only true and wide sense, so should palaeontology be regarded 
as a branch of zoology in its wide sense. But while the 
greatest scientific successes have been achieved by those re- 
search students who have treated their particular subject from 
this wider aspect, we find in the universities that palaeontology 
is often relegated to the care of a geological specialist. Cuvier 
and Lamarck in France, and Richard Owen, Wallace, Huxley, 
Ray Lankester, Alleyne Nicholson have been brilliant ex- 
ponents in Great Britain of the higher and wider scope of 
zoology. But comparatively few individuals have such a 
thorough grasp of zoological and geological knowledge as to 
enable them to treat palaeontological researches worthily, and 
there has accumulated a dead weight of stratigraphical-palaeonto- 
logical literature wherein the fossil remains of animals are 
named and pigeon-holed solely as an additional ticket of the 
age of a rock-deposit, with a wilful disregard of the much 
more difficult problem of their relationships in the long chain 
of existence. 

The terminology which has been introduced in the innumer- 


able monographs of special fossil faunas in the majority of 
cases makes only the slenderest pretext of any connection 
with recent systematic zoology; if there is a difficulty, then 
stratigraphical arguments are made the basis of a solution. 
Zoological students are, as a rule, too actively engaged and 
keenly interested in building up new observations to attempt 
to spell through the arbitrary palaeontological conclusions 
arrived at by many stratigraphers, or to revise their labours 
from a zoological point of view. 

Until the sixth decade of the nineteenth century the 
exact description of genera and species received the chief 
attention in the literature both of zoology and stratigraphical 
palaeontology. The individual faunas and floras of the past 
time were regarded by the adherents of the Catastrophal 
Theory as creations quite distinct from one another, whose 
order of succession and whose mutual relations it was the 
first duty of stratigraphy and palaeontology to determine. In 
a prize essay of the Paris Academy, entitled " Investigations of 
the developmental laws of the organic world during the period 
of formation of our Earth's Surface" (Stuttgart, 1858), H. G. 
Bronn has supplied a valuable compendium of all the known 
palaeontological material and the distribution of the fossils in 
the different strata. 

In this work Bronn criticises unfavourably the theories of 
creation and development advanced by Lamarck, GeofTroy 
Saint-Hilaire, Oken, Grant, and others. He admits that 
modifications of organic forms may produce racial distinctions, 
but regards as fallacious, or at least wholly hypothetical, the 
generatio cequivoca, the gradual modification of species, the 
descent of all younger forms from older, as well as the evolu- 
tion of more highly-perfected organisms from those on a lower 
platform of organisation. He assumes a creative force which 
not only brought forth the first organisms, but had continued 
during subsequent geological epochs to the present age, and 
had worked independently of chance circumstances and accord- 
ing to a definite plan. The unity of this plan was the basis 
of the apparent relationships between the types of successive 
creations ; as certain types became extinct, others were created 
of similar but more perfect design to replace the gap in the 
organic world. Thus, by repeated substitutions, as Sedgwick, 
Hugh Miller, Brongniart, and Agassiz had already advocated, 
Bronn tries to explain the universal tendency in animate 


creation towards the improvement of the type. Bronn recog- 
nises the frequency of so-called " mixed forms " uniting in 
themselves features which subsequently are distributed and 
specialised in different related genera or families, but he takes 
such forms to be incontrovertible evidence of the law of the 
introduction of improved forms. 

As far back as 1849, L. Agassiz had distinguished progressive, 
prophetic, synthetic, and embryonic types among fossil organ- 
isms, and had attributed great importance to the prophetic 
and embryonic types as fore-runners and signs of coming 
changes in the organised relations. A similar conception was 
afterwards conveyed by Richard Owen in his definition of 
"plan forms" or "archetypes." 

Both Agassiz and Bronn gave particular attention to the 
grades of differentiation and complexity, and to the systematic 
rank of an animal type, and enunciated fundamental principles 
of animal organisation. In 1854, Edward Forbes for the first 
time in literature pointed out the significance of degeneration, 
or retrogression of types, as shown in certain groups of animals. 

According to Bronn, two fundamental principles have guided 
the whole succession of organisms from the oldest geological 
period to the present time : first, an extensive and intensive 
productive force continually increasing in power ; and second, 
the nature and the variations of the external conditions. With 
remarkable skill and ingenuity, Bronn elucidates the circum- 
stances and events upon which the activity of the productive 
force is dependent, as well as the varying conditions of the 
atmosphere, the climate, the distribution of land and water, 
the configuration of the successive land surfaces in the past 
ages, and the influence of the varying conditions on the 
animate creation. He infers from these considerations the 
law of terripetal development. From a primaeval ocean rose 
cliffs, islands, and continents ; the fauna of a universal ocean 
was succeeded by the first settlement of land animals and 
plants ; as the islands and continents increased in size, and 
denudation altered their surfaces, new conditions of existence 
were provided for terrestrial and fresh-water inhabitants, and 
more complex correlations and differentiations of parts were 
rendered possible. The faunas and floras of the older geo- 
logical periods bore a tropical impress : the temperature cooled 
very slowly, and as the conditions approached more nearly to 
those of the present age, the strange-looking orders, families, 


genera, and species of the earlier ages gradually became ex- 
tinct and were replaced by those of to-day. 

But whereas Cuvier, Agassiz, D'Orbigny, and other sup- 
porters of the Catastrophal Theory had supposed the faunas 
and floras of any one geological period to be sharply defined 
from those of the foregoing and succeeding ages, and in fact 
to have no species in common, Bronn insisted that a smaller 
or larger number of genera and species passed from one age 
to the next, and have been in a measure connecting intermediate 
links. The creation of new types and the extinction of old 
types had not been confined to a few "days" or "periods" 
of creation associated with great earth catastrophes, but had 
been continually and quietly going on as a consequence of the 
changes in the external conditions of existence which had 
been likewise continuously in progress during the whole 
geological history of the earth. At the same time Bronn 
allowed that certain surface changes had been the cause of 
more far-reaching variations of form than others. The period 
of existence that had been assigned to the fossil species was 
extremely unequal ; as a rule, however, it had been very long. 
The limits of the geological horizons, formations, etc., are 
neither in palaeontological nor in geographical or lithological 
respect absolutely sharp, but are frequently more or less in- 

The able arguments of Bronn opened up a series of ques- 
tions which until his time had either been entirely neglected by 
palaeontologists, or had never benefited by a frank and lucid 
expression of their difficulties. Bronn's teaching was in close 
harmony with Charles LyelPs doctrine of the uniformitarian 
development of the earth ; more especially Bronn's insistence 
upon the continuity in the processes of change, and his scien- 
tific demonstration of transitional species and genera bridging 
the supposed gaps in the palaeontological and stratigraphical 
succession provided a stepping-stone for the acceptance of 
Darwin's grander principles. When, in the year 1859, Darwin's 
epochal work On the Origin of Species by means of Natural 
Selection appeared, it was Bronn who was one of the first in 
Germany to recognise it as the outcome of an extraordinary 
genius, and he immediately translated the work into the 
German language. 

The publication, in 1866, of Ernst Haeckel's work on 
General Morphology was the first practical application of 


Darwin's theory to zoological classification, and it exerted 
a widespread influence both in extending the knowledge of 
Darwin's leading principles and in demonstrating the great 
superiority of a scheme of classification based upon these 
principles over the many artificial schemes which had been 
previously proposed on the basis of recurrent earth cata- 
strophes, or on that of repeated exhibitions of the creative 
force and the working of inscrutable laws. 

A decade after the publication of the Origin of Species^ 
Darwin's theory of descent was almost universally accepted 
as the most natural basis of classification in all the domains 
of the science of animal organisms. Darwin's conception of 
the origin of species could not fail to enhance the interest of 
palaeontology. That study was realised to be no longer merely 
descriptive and comparative, or the means of bringing useful 
material to the sciences of botany and zoology, but a branch 
of knowledge to be studied for its own intrinsic interest. 

The greatest likelihood of solving some of the obscure 
problems of the origin and extinction of species lay with the 
palaeontologist, since the rich material at his command, ex- 
tending through many successive ages, comprised the record 
of the incoming and outgoing of countless types of life. The 
origin, geological development, gradual modification, differ- 
entiation, improvement or degeneration of the individual 
groups of the animal and plant kingdom, the genealogical 
relations of the primaeval and recent organisms, the phylogeny 
of the plant and animal world, the relations between the 
developmental history (ontogeny) of the single individual, 
and the history of descent (phylogeny) of the family, order, 
and class to which the individual belongs, are questions which 
can be answered either exclusively by palaeontology or only 
with its assistance. 

With Darwin begins the modern period of palaeontological 
research. Numerous and important evidences were brought 
forward in favour of the doctrine of descent. The continuous 
series of forms, which can be followed through several strati- 
graphical horizons and formations with greater and less 
variations, the occurrence of mixed and embryonic types, 
the parallels of ontogeny with the chronological succession 
of related fossil forms (biogenetic principle of Haeckel), the 
similarity in the general impress of the fossil floras and faunas 
next each other in age, the agreement in the geographical 


distribution of the existing organisms and their fossil ancestors, 
as well as many other facts, are only comprehensible on the 
assumption of the doctrine of transmutation. 

Palaeontology has taken an active part since 1870 in the 
establishment of the theory of descent, and at the present 
day phylogenetic problems are regarded as one of the chief 
charms in palaeontological research. The character of 
palaeontological literature has been correspondingly modified ; 
the purely stratigraphical treatment of palaeontological results 
has been held more and more distinct from the biological- 
systematic treatment, and the latter places the genealogical 
direction of research more and more in the foreground. The 
literature has been so extensively increased, and has been 
contributed in so many different languages, and often cir- 
culated in so few copies, that very great difficulties stand in 
the way of obtaining a complete general survey of its results. 
The older text-books of Bronn, D'Orbigny, Geinitz, Quenstedt, 
Giebel, Nicholson, and others were rapidly out of date, and 
were partially designed only to meet the requirements of 

The Handbuch der Palaontologie of Karl A. von Zittel, the 
botanical part of which was written by W. Schimper and 
A. Schenk, endeavours to provide a general survey of 
palaeontological subject-matter in harmony with the modern 
standpoint of zoology. The original intention of the author 
was to comprise Palaeozoology in one volume, but as the work 
proceeded it extended to four thick volumes, and the 
completion of the work occupied seventeen years (1876-93). 
The chapter on fossil insects was contributed by S. Scudder, 
Throughout the entire work a primary object has been to 
point out the close relationships between palaeontology and 
the other branches of biological science (Zoology, Comparative 
Anatomy, Botany, Embryology), and to make application to 
palaeontology of the data acquired by those sciences. The 
subject-matter is therefore arranged in strict systematical order, 
and the enumeration of each particular group of forms is 
preceded by an introduction elucidating the main features of 
the organisation. The histological structures are described in 
much fuller detail than in any of the former text-books of 
Palaeontology. In the special systematic portion, all well- 
founded genera are accepted and described, the doubtful 
genera are eliminated or only briefly mentioned. The 


systematic account of each larger group of forms is followed 
by a brief sketch of the geological distribution and the 
phylogeny of the foregoing forms. Importance is given to the 
data which afford evidence of the genetic connection of the 
members of individual branches, classes, orders, and families ; 
but the representation is kept free from bias towards one 
direction of thought or another. Where palaeontology can 
bring forward no evidences in favour of the doctrine of 
evolution, or where considerable gaps occur in the palaeonto- 
logical sequence and seem to speak rather for the opposite 
views, the authors have consistently endeavoured to set forth 
the actual facts with full impartiality. 

Zittel's Handbook has served as a model for nearly all the 
more recently published smaller text-books, such as those of 
Hoernes (1884), Steinmann-Doderlein (1890), Bernard (1895), 
Zittel (1895), and Smith-Woodward (1898). 

Two works of very great interest have been added to 
geological and palseontological science by Neumayr. 1 The 
one is his Erdgeschichte, and is full of original and suggestive 
conceptions ; the other is his Stdmmen des Thierreichs, which 
unfortunately remained unfinished. The published portion, 
which comprises the groups of the Protozoa, Ccelenterata, 
Echinodermata, and Molluscoida, introduces many new points 
of. view, and will have a permanent value both for palaeontology 
and zoology. 

Probably the most influential disciple and exponent of the 
theory of descent was the great English zoologist, Thomas 
Huxley. Cope in America, Gaudry in France, and Haeckel 
in Germany are zoologists who have likewise been in the fore- 
front of the new teaching. 

Huxley's palaeontological works, like those of Gaudry and 
Cope, are mostly devoted to the vertebrate animals, and are 
distinguished by his remarkable acuteness of observation and 
his genius for inductive combination. His determination of 

1 Melchior Neumayr. born in Munich on the 24th October 1845, the 
son of a high state official, studied in Munich and Heidelberg; after he 
graduated, he entered in 1 868 the Imperial Geological Survey Department 
at Vienna, and contributed several special papers on the geology of various 
areas of Hungary, Transylvania, and North Tyrol; in 1872 became a 
University tutor in Heidelberg, but in 1873 was called to Vienna to be 
Professor of Palaeontology, a chair which had been founded especially for 
him. In the midst of his labours, he died on the 29th January 1890, of 
heart disease. 


the genealogy of the horse, his elucidation of the genetic 
relations of birds and reptiles, his memoir on Crossopterygia, 
are among the classical productions of palaeontological and 
zoological science. The works of Gaudry deal with the 
genealogical relations of the different classes of animals and 
their descent from primseval ancestors, and are written so 
convincingly, and with such elegance of style, that they have 
roused an interest for palaeontology in the widest circles. 
Scientific interest is chiefly concentrated upon his admirable 
contributions to the genealogies of the fossil Vertebrates. 
E. D. Cope, 1 together with Herbert Spencer, may be regarded 
as the head of the Neo-Lamarckian School, which has a strong 
foothold in North America. In opposition to Darwin, the 
gradual changes in the organic creation are not explained as 
the result of natural selection, but chiefly attributed to the 
influence of use and disuse of parts, and also to the influence 
of the external environment, such as the supply of nourishment, 
climatic conditions, mechanical agencies, etc. Upon these 
principles Cope has attempted to explain the Kinetogenesis or 
gradual evolution and modification of the skeletal structures 
and teeth of Vertebrates. More recent work by H. F. Osborn, 
carried out in accordance with Cope's conceptions, has attained 
a certain success. 

Amidst the very large number of special memoirs and books 
which treat individual sub-divisions and groups of fossil animals, 
it is only possible here to single out those which have exerted a 
marked influence upon the progress of systematic palaeozoology, 
or on the phylogenetic relations of fossil faunas. 2 

1 Edward Drinker Cope, born 1840 in Philadelphia, belonged to an old 
and wealthy family ; as a boy he was fond of travel, and at nineteen years 
of age he published a valuable zoological memoir on Batrachians. On the 
conclusion of his studies in Philadelphia, he made a journey to Europe in 
1863 to become acquainted with the European museums. In 1864 he 
accepted the post of Professor of Comparative Anatomy at Haverford 
College, but he resigned it in 1867. From 1865 onward, Cope devoted 
his time chiefly to the study of fossil Vertebrates, and partly at his own 
expense, partly as a member of the Hayden and Wheeler Expeditions, he 
made exploring tours in search of material through Kansas, Colorado, 
Wyoming, New Mexico, and Texas, at the same time producing a large 
number of memoirs. In 1889 he was appointed Professor of Geology and 
Mineralogy at the Academy in Pennsylvania; he died on the I2th April 
1897. His large collection of fossil Mammalia was secured by the 
American Museum in New York. 

2 The works mentioned in the following pages are fully cited in the 
references subjoined to Zittel's Handbook. 


Protozoa. The fossil remains of Protozoa are naturally con- 
fined to those classes or orders which are shell-producing 
during life. The most widely distributed fossil representatives 
of the Protozoa are the Foraminifera or Polythalamia (Reti- 
cularia, Carpenter), which enter largely into the composition 
of many marine limestones, and whose occurrence has been 
known for several centuries to natural historians. The earlier 
memoirs of Breyn (1732), Soldani (1780), Fichtel and Moll 
(1803), Lamarck (1804-7), Denys de Montfort (i 808-10), 
wherein a considerable number of these small forms are 
described and figured, were followed by the more compre- 
hensive investigations of Alcide d'Orbigny (1824). These 
for the first time made the attempt to introduce a systematic 
order and classification into this group of testaceous organisms, 
which were still almost universally regarded as mollusca, 
belonging to the group of cephalopods. 

D'Orbigny distinguished two main groups among the Poly- 
thalamia, one of which (Siphonifera) contains the chambered 
shells of the true cephalopods, while the other (Foraminifera) 
embraces the shells characterised by the perforations in the 
dividing walls of the chambers. The Foraminifera are then 
sub-divided by D'Orbigny chiefly according to the external 
features of the shell, and the number and arrangement of the 

A number of the species enumerated in the Tableau Method- 
ique have been made known far and wide by enlarged models, 
which were distributed to various academies in 1825 and 1826. 
D'Orbigny also contributed a monograph on the fossil Forami- 
nifera in the Tertiary deposits of the Vienna basin. 

The advance effected by Ehrenberg's microscopic examina- 
tion of thin slices of Foraminifera has already been mentioned 
(p. 326). But although so accurate an observer, Ehrenberg 
formed fallacious views respecting the organisation of the 
group, and thought the Foraminifera might belong to the 
Bryozoa. Dujardin in 1835 contested many of Ehrenberg's 
conclusions, and demonstrated that the Foraminifera belonged 
to the Rhizopoda. Williamson, Reuss, and especially W. B. 
Carpenter, objected to the previous schemes of classification 
which had been formulated merely upon external features of 
the skeleton and habits of growth. The investigations of 
Williamson on the fine details of structure, and the famous 
work by Carpenter on the Microscopic Structure and Classifica- 


tion of the Foraminifera^ completely overthrew the older 
classifications and formed the basis of our present intimate 
knowledge of these exquisite little shells. 

Carpenter divided the Reticularia into two sub-classes : 
Imperforata and Perforata, and sub-divided each of these sub- 
classes into several families distinguished according to the 
chemical composition and microscopic structure of the tests. 
The views held by Carpenter and his collaborators, Parker and 
Jones, regarding the confines of the genera and species, 
differed very considerably from those of D'Orbigny, as the 
English zoologists often comprised under the same generic 
title forms very different in their external appearance, on the 
plea that they were connected by intermediate types. 

Reuss has published from 1839 onwards a large number 
of papers, mostly in the Transactions of the Vienna Academy, 
describing individual species of fossil Foraminifera from 
all geological formations. The works of Parker and Jones, 
extending from the year 1857, follow the same direction 
of special research. The classifications of Schwager and 
Brady introduced several modifications of Carpenter's scheme. 
Brady pointed out that the sub-classes Imperforata and Per- 
forata could not be so sharply defined as had been done by 
Carpenter, for example the group Lituolidea, which Carpenter 
had ranked under the sub-class Imperforata, included also 
certain species which were finely perforate. This matter, 
along with other systematic difficulties, has been more recently 
discussed by Ray Lankester, in his descriptive and classifi- 
catory account of the Protozoa, published in the Encyclopaedia 
Britannica. Brady's Report on the Foraminifera of the Chal- 
lenger Expedition, and his monograph of the Foraminifera in 
the Carboniferous Limestones of Great Britain, are two of the 
finest productions in this domain of research. 

In the French literature of the Foraminifera, the excellent 
monograph of the Nummulites by D'Archiac and Haime takes 
the highest place. Terquem and Berthelin even at the present 
time are wholly disciples of D'Orbigny. Meunier-Chalmas 
and Schlumberger have, on the other hand, placed great 
significance on microscopic researches of the shell-architecture, 
and have made many interesting observations on dimorphic 
forms of the initial chamber. In Italy, Michelotti, Seguenza, 
Silvestri, and more particularly Fornasini, have described the 
Foraminifera present in the younger Tertiary deposits. 


From a Photo by\ 

{Elliott & Fry, Baker St., W. 


In addition to the Foraminifera, the Radiolarians with 
siliceous or chitinous tests represent another class of Protozoa 
which come under consideration in palaeontological researches. 
The knowledge of the Radiolaria does not extend so far back 
as that of Foraminifera. The earliest accounts of these micro- 
scopically minute organisms were given by Tilesius (1806) 
and by Meyer (1834); but Ehrenberg was the first investigator 
who disclosed the wonderful variety and beauty of their sili- 
ceous skeletons. In a series of special monographs and 
magazine articles extended over a long period of years from 
1838 to 1875, Ehrenberg described many hundred forms 
belonging to this group, which he had called Polycystina. His 
material had been collected from recent oozes on the ocean- 
floor, and from the Tertiary marls of Sicily, Zante, Oran, 
North America, and Barbadoes, the last-mentioned locality 
alone providing 278 species. But Ehrenberg had very obscure 
notions about the organisation of the Polycystina. 

The living structure and the systematic position of this 
group were elucidated by Huxley in 1851. A fuller exposition 
of the zoological aspects was given in 1855 by Johann Miiller, 
who suggested the term of Radiolaria as better suited for the 
group than Ehrenberg's name of Polycystina. The beautifully 
illustrated monograph of the Radiolaria by Ernst Haeckel 
erected a complete classificatory system for the Radiolaria, 
and won universal admiration for the artistic representations of 
the infinite diversity in the skeletal forms produced by these 
simple organisms. 

Haeckel's works are chiefly devoted to recent Radiolaria, 
and at that time, in 1862, science was only cognisant of the 
occurrence of fossil Radiolaria in the Tertiary deposits. 
Zittel, in 1876, described some older forms from Upper Cre- 
taceous strata, and between 1885 and 1892 D. Riist carried 
out a long series of researches, preparing microscopic sections 
of siliceous rocks from all the geological formations ; he suc- 
ceeded in demonstrating the presence of numerous Radio- 
larian species from the Cambrian or oldest Palaeozoic 
formation onwards to the present age. 

Brief mention must be made of a controversy that arose 
regarding certain structures thought to represent the oldest 
known animal organism. In the year 1858 MacCulloch col- 
lected in the Laurentian gneiss of Canada curious aggregates 
of serpentine and calcite, arranged in irregular alternate 



layers, the serpentine having rather a reticulated distribution 
in a ground-mass of calcite. Logan regarded such aggregates 
as altered masses of an originally organic growth, and in 1864 
Sir William Dawson described these reticulate structures as 
the ramification of a Foraminiferal growth under the name 
of Eozoon Canadense. This view was supported by Car- 
penter in 1876, and was afterwards confirmed by Parker, 
Jones, Brady, Reuss, and other specialists, whereas King, 
Rowney, and Carter contended that the supposed Eozoon was 
not an organic structure, but had been produced by processes 
of mineralogical segregation. The controversy continued for 
many years, until Moebius, of Kiel University, published what 
is considered by most geologists a decisive paper in favour 
of the inorganic origin of the Eozoon structure. Moebius 
contended that the serpentine matter of the "Canal System" 
had been infiltrated into the calcite along fine vein-fissures 
disposed in the calcareous rock with exceptional regularity. 

Sponges. No group among the Invertebrates resisted 
scientific treatment so long as the fossil sponges. This is 
scarcely surprising, when it is remembered that zoologists 
were still in doubt in the early part of the nineteenth century 
whether the marine sponges belonged to the vegetable or 
animal kingdom. The pioneer investigations of Robert 
Grant (1825) first afforded a true conception of the organisa- 
tion of these creatures ; and after Grant, several English 
scientists among others, Johnstone, Bowerbank, and Carter 
made important advances towards securing a better grasp of 
the morphology and systematic relations of the group. 

The backward state of zoological knowledge of living sponges 
made it almost impossible for palaeontologists to attempt any- 
thing more than a description and illustration of the fossil 
sponges. The first volume (1826) of the Petrefacta Germanic 
of Goldfuss and Miinster included seventy-five species of fossil 
sponges, which the authors distributed under eleven generic 
names; but the work of Goldfuss shows little advance on the 
works of earlier writers, Guettard, Parkinson, Mantell, and 
others. The works of Michelin (1840-47) and Blainville also 
yield merely descriptions of the external form, without any ac- 
count of the finer structural features. These authors take the 
same standpoint as Goldfuss, in assuming that the fossil 
sponges are ancestral forms of the living ceratose sponges, in 


which the horny fibres had been changed to stone by means of 
the processes of petrefaction. Similarly, the works of Geinitz, 
Klipstein, Pusch, Reuss, Quenstedt, and Roemer increase 
the knowledge of the endless diversity of form presented by 
sponges, but add little to a scientific comprehension of their 

A notable position in the older literature of sponges is 
taken by the two short memoirs of Toulmin Smith (1847-48), 
wherein the structure of the Ventriculites from the white chalk 
is fairly accurately represented. Owing, however, to the fact 
that the nearest allies among living sponges, the Hexactinellids, 
were unknown at the time of his investigations, Smith drew 
fallacious inferences regarding the nature and systematic 
position of these fossils. He compared them with Bryozoa. 

In the year 1851, D'Orbigny devised a badly-arranged 
scheme of classification for fossil sponges, upon the basis solely 
of external features. He called all fossil sponges " Petro- 
spongiae," and contrasted them with recent sponges, ascribing 
to fossil sponges an originally stony skeleton composed of 
calcareous fibres. According to D'Orbigny, the petrospongiae 
form a curious and extinct sub-division of the sponges. This 
erroneous conception of D'Orbigny's was shared by Fromentel, 
but the latter author, in differentiating genera and species, made 
use of differences in the canal system and in the kinds of pores 
and openings at the surface. Friedrich Roemer followed 
Fromentel's method, and he differentiated between sponges 
with fenestrated skeletal structure and sponges with a skeleton 
composed of " worm-shaped fibres." Pomel also made careful 
observations of the skeletal structures so far as those could be 
distinguished with the naked eye or by the aid of a hand-lens. 

The deep-sea investigations of the last part of the nineteenth 
century initiated a new era in the investigation of sponges, 
recent and fossil. Wyville Thomson, the leader of the 
Challenger Expedition, was the first to point out the similarity 
in the structures of fossil ventriculites and living silicispongiae. 
In 1870, Oscar Schmidt, by the method of etching Jurassic 
and Cretaceous specimens, demonstrated in fossil forms the 
presence of certain skeletal structures similar to those of 
existing hexactinellids and lithistids. Nevertheless the fossil 
sponges still presented an apparently distinct and well-defined 
group, until almost simultaneously Zittel and Sollas resolved to 
apply Nicol's method and prepare thin slices of the fossil 


material for microscopic examination. In 1877, Sollas demon- 
strated, by his examination of several genera belonging to the 
English chalk, the identity of their structure with that of living 
hexactinellids, lithistids, and monactinellids. Zittel, in 1876, 
published his microscopic investigations embracing the whole 
of the fossil sponges, together with a monograph of the genus 
Coeloptychium. In this work, as well as in the studies 
published during the following year, it was fully demonstrated 
that all fossil sponges could be included in the scheme of 
classification erected for existing sponges. Zittel succeeded in 
showing that a large number of sponges referred to the Calci- 
spongiaa by previous authors had been originally arenaceous, 
but the sandy material had been dissolved, and in its place 
calcareous substance had been laid down. This removed the 
greatest difficulty in the study of fossil representatives of the 
Silicispongiae. Zittel also demonstrated the true calcareous 
structures of numerous fossil Calcispongiae, whose existence 
had been called in question by E. Haeckel in his monograph of 
the Calcispongiae (1872), and in spite of much contradiction at 
first, Zittel's evidence ultimately received general acceptance. 

The application of the microscopic method, which had been 
used by Zittel and Sollas, was followed in almost all the later 
publications on fossil sponges, and the classification proposed 
by Zittel for recent and fossil sponges was confirmed in its 
main features and further improved by the zoological and 
anatomical investigations of O. Schmidt, F. E. Schulze, Carter, 
Vosmaer, Lendenfeld, and others. 

The most distinguished students of fossil sponges at the 
present day are G. J. Hinde and Hermann RaufT. The former 
has published a monograph of the fossil sponges (1884) in the 
Natural History Collection of the British Museum, and is at 
present engaged on a monograph of the fossil forms of Great 
Britain, parts of which have appeared since 1887 in the 
publications of the Palaeontographical Society. Kauff has 
produced in his Palceospongiology (1893) an exemplary repre- 
sentation of all the palaeozoic forms of sponges. 

C&hnterates. Up to the year 1825 there was great in- 
security about the organisation of the organisms at present 
comprised under the group of the Coelentera. The schemes of 
classification attempted by Lamouroux, Esper, Lamarck, and 
others are full of errors; the researches of Ehrenberg and 


Milne-Edwards first revealed the anatomical structure of 
zoophyte organisms, and made it possible to differentiate them 
from a number of other forms with which they had been 
erroneously included in previous classificatory systems. 
Ehrenberg based his classification of coral zoophytes exclu- 
sively on the characters of recent corals, more especially on his 
examination of the Red Sea corals. The number of tentacles 
was, in his opinion, the leading feature of distinction; according 
to it he erected the main sub-divisions of his classification. 

Fossil corals were described and figured in most of the 
larger palnsontological works that appeared during the first 
half of the nineteenth century. The illustrative plates of 
Golclfuss (1826), Michelin (1841-47), Lonsdale and MacCoy 
display a large number of fossil species, but notwithstanding 
the advances that were being made in the knowledge of living 
corals, the systematic treatment of fossil corals in these works 
is as crude and antiquated as in the much earlier works of 
Guettard, Parkinson, and Schlotheim. The profound and 
exhaustive works of Milne-Edwards l and Haime revolutionised 
the study of corals. These scientists made a thorough investi- 
gation of the organisation of living polyps, and from that 
proceeded to examine group after group of the fossil corals, 
directing attention equally to the evidences afforded by the 
skeleton regarding the original form and structure of the fossil 
polyps, and to the phylogenetic indications given by the 
occurrence and distribution of the fossil faunas in the strati- 
graphical succession. The penetrating critical instinct and 
unbiassed judgment of the authors produced a work which is 
recognised to be one of the most skilful that has ever appeared 
in scientific literature. The classificatory system of Milne- 
Edwards and Haime is based upon the character of the septa 
and the mode of their increase in number, and with a few 
modifications, the system has remained until the present day. 

Later works on fossil corals for the most part dealt with 
the coral faunas of particular localities or of a particular 
stratigraphical horizon. Of special value are the monographs 
of Reuss, Fromentel, De Koninck, Koby, Hall, Becker, 

1 Henri Milne-Edwards, born 1800 in Bruges, studied medicine in 
Paris, and was at first the Professor of Natural History in the College 
Henri IV., then in 1841 at the Museum. In the year 1862 he was 
appointed Professor of Zoology, and two years later Director of the 
Museum; died 1885 in Paris. 


Milaschewitsch, D'Archiardi; and Duncan's book on British 
fossil corals has enjoyed a wide circulation. Quenstedt alone 
adheres both in his text-books and Mis Paleontology of Germany 
(vol. vii., 1889) to the old system of Ehrenberg, and continues 
to group the Bryozoa along with the corals. 

A short but very important paper was published in 1869 
by A. Kunth. This observer pointed out the fundamental 
difference in the method according to which new septa had 
developed in the Palaeozoic group of the Rugosa, as compared 
with the order of intussusception of the septa in the younger 
corals; and he showed how with this difference was associated 
the bilateral symmetry of the Rugose corals on the one hand, 
and the radial symmetry of the younger corals. After the 
publication of Kunth's memoir, the Rugose corals, also known 
under the synonyms of " Tetracorallia " or " Pterocorallia," 
were treated as an independent group in the classification of 
corals, distinct from the younger group of " Hexacorallia," for 
which Milne-Edwards' and Haime's observations still held good. 
Kunth's work gave a new impulse to the study of the Rugose 
group of Palaeozoic corals, and was followed by a number of 
special memoirs, those of Dybowski, Nicholson, Schliiter, 
Lindstrom, and Freeh, among many others. 

In 1872, Lacaze-Duthiers made known his valuable embryo- 
logical investigations, which necessitated a new revision of the 
laws of septal symmetry enunciated by Milne-Edwards and 
Haime. The discoveries made by L. Agassiz and Moseley 
regarding the zoological relationship of Millepora and Helio- 
pora entirely overthrew the group of Tabulata as it had been 
defined in the system of Milne-Edwards and Haime. And 
Dybowski, Roemer, Nicholson, and other leading authorities 
on Palaeozoic corals then endeavoured by the most detailed 
investigations of the growth-relations, the organisation, and 
finer structure, to explain the remarkable diversity of forms 
comprised in this group. 

The microscopic structure of the calcareous skeleton had 
been little taken into consideration by Milne-Edwards and 
Haime. In 1865, Kolliker first directed attention to it; in 
1882, there followed almost simultaneously the works of Pratz 
and Koch, showing illustrations of microscopic sections, and 
a similar method was followed by Nicholson, Freeh, Volz, 
Felix, Struve, and others. The most comprehensive investiga- 
tion into the microscopic structure of the skeleton of living and 


fossil corals has been contributed by Maria M. Ogilvie (1896). 
Upon the basis of her comparative microscopic researches, the 
authoress suggested certain classificatory reforms which appear 
to weaken very materially the strong distinctions previously 
drawn between the Tetracorallia and Hexacorallia, as well as 
between the Hexacorallian sub-divisions of Aporosa and Per- 
forata. The special examination of a large number of inter- 
mediate forms among Jurassic corals also enabled her to bring 
forward many evidences of the phylogenetic relationship of 
Tetracorallian and Hexacorallian types. 

After Moseley (1877) had published his treatise on Millepora, 
and in the same year J. Carter had pointed out the close 
relationship of Hydraciinia, Parkeria, and Stromatopora, a 
number of organisms which had been consigned variously to 
the Bryozoa, and sometimes to the group of Foraminifera, were 
recognised as Hydrozoa. Steinmann (1878) and Canavari 
(1893) described new fossil genera from Jurassic and Cretaceous 
deposits, Bargatzki (1881) described the Stromatoporoids in 
the Devonian series in the Rhineland, and Nicholson (1886-92) 
published a monograph of all known Stromatoporoids. The 
GrapioliteS) an extinct group of Hydrozoa confined to the 
oldest fossiliferous deposits (Silurian and Cambrian), have 
been the subject of very careful palseontological investigations. 
They were taken for Cephalopods by Wahlenberg and Schlo- 
theim, and for Foraminifera by Quenstedt, while others placed 
them amongst Alcyonarians. Portlock (1843) was the first to 
recognise their resemblance to the Sertularians. Barrande 
published (1850) the earliest detailed account of the Bohemian 
Graptolites, but still compared them with the Pennatulids. 
The works of Suess, Scharenberg, Geinitz, and Richter 
extended the knowledge of Graptolites only in a moderate 
degree; on the other hand, an excellent monograph of the 
Graptolites occurring in the " Quebec Series " of rocks was 
contributed by J. Hall in 1865, adding a number of new, 
well-preserved species to the group, and affording much im- 
portant information regarding the organisation and zoological 
position of Graptolites. 

In the year 1872 Nicholson gave an admirable survey of 
all the facts known about Graptolites, and in 1873 the first 
communications appeared by Lapworth. The researches of 
this acute observer were continued until 1882, and revealed 
many new and important data respecting the structure, the 


development, the growth, relations, and geological distribution 
of the Graptolites. All later writings on Graptolites are based 
upon the results obtained by Lapworth. During the last few 
years Holm and Wimann have by means of novel methods 
of technique determined the finest structural features of different 
Graptolite genera, and R. Riidemann (1895) made some for- 
tunate discoveries which threw light on the mode of life and 
the relationship of these remarkable organisms. 

Fossil Medusas are of very rare occurrence ; well-marked 
impressions found in the lithographic shales of the Franconian 
Jura Chain have been carefully described by Beyrich (1849), 
Haeckel (1865-70), and Ammon (1883). Nathorst in 1881 
assigned to the Medusas certain casts in the Cambrian sand- 
stone of Sweden, and quite recently (1898) Walcott described 
a large number of cast structures in the Cambrian deposits 
of North America as of Medusa origin. 

Echinoderms. In the eighteenth century Klein had proposed 
for the sea-urchins the class name of Echinodermata. Cuvier 
united under the same class the Ophiuridea or sand-stars, 
the Holothuridea or sea-slugs, and the Encrinites^ without, 
however, recognising the Encrinites as a separate sub-division. 
In 1821, J. S. Miller, a native of Dantzig although resident in 
Dublin, published an excellent monograph on all the fossil 
Sea-lilies or Encrinites then known, and combined them into 
an independent sub-division or order which he named 
Crinoidea. In 1828, Fleming erected the order of Blasioidea 
for the Pentremites which had been discovered in 1820 by Say 
in the North American Carboniferous Limestone, and in 1845 
Buch erected the order of Cystidea for a group of fossil 
Crinoids then very little known. Thus the limits and the 
chief orders of the Echinodermata were definitely established, 
and at the suggestion of Leuckart in 1848 the class Echino- 
dermata, which had hitherto been treated systematically as 
closely allied with the Ccelenterata, was represented as an 
independent branch of descent in the animal kingdom. In 
addition to Leuckart's fundamental differentiation of these two 
animal classes, it was he who first combined the Crinoidea, 
Cystoidea, and Blastoidea under a common group -name 
Pelmatozoa,) and placed it in contradistinction to the other 
sub -divisions of Echinodermata, the Echinidea, Asteridea, 
Ophiuridea, and Holothuridea. 


The systematic study and morphology of the Pelmatozoa 
was greatly advanced by J. S. Miller's Monograph of the 
Crinoidea, which masterly work constructed a secure basis for 
all future inquiry into the morphology of the group. Miller 
made application of the architectural arrangement of the plates 
in the calyx as a basis of classification, and recent researches 
have frequently found it advantageous to revive leading features 
in Miller's classification. 

Goldfuss and Miinster added a number of new specific 
descriptions to the knowledge of Crinoidea, but made no 
attempt to elucidate the structural relations. Three important 
memoirs were contributed by the anatomist, Johann Miiller, on 
the structure of Pentacrinus (1841), on Comatula (1847), and 
on the structure of Echinoderms generally (1853). These 
memoirs were published in the Transactions of the Berlin 
Academy, and for several decades formed the groundwork of 
further zoological investigations in this group. Miiller included 
the study of fossil forms in his researches, and he sub divided 
the known Crinoidea into three sub-orders Tesselata, Arti- 
culata, and Costata. 

Almost simultaneously with Miiller's works there appeared 
in England a monograph of fossil and recent Crinoids by the 
two Austins (1843). But in spite of many new and valuable 
observations, this work was unsuccessful, on account of its sub- 
division of Crinoids into stalked and unstalked groups. This 
sub-division was regarded as quite artificial, seeing that the 
gifted zoologist, Vaughan Thomson, had in 1836 demonstrated 
the development of the genus Comatula from a larval stage 
resembling a stalked Pentacrinus. 

The anatomical structure of the living Pentacrinus was 
described by Liitken (1864), and that of the Comatulids was 
elucidated by the researches of Wyville Thomson (1865) and 
W. B. Carpenter (1866). The deep sea explorations off the 
coast of Norway led to the discovery of Rhizocrinus, and the 
detailed investigation of this interesting genus, carried out by 
Sars (1868) and Ludwig (1877), met with a cordial reception 
in palaeontological circles. 

Numerous monographs and shorter papers on Palaeozoic 
Crinoidea were meanwhile being published ; among the more 
voluminous writers on this subject were De Koninck and Le 
Hon (1854), Hall (1847-72), Roemer (1860), Ludwig Schulze 
(1866), Meek and Worthen (1866-75); Mesozoic Echino- 


dermata were described by D'Orbigny (1840) and Beyrich 
( l &57)- Quenstedt's Paleontology of Germany (vol. vi., 
1874-76) contains an abundance of new detailed observations 
but retains the older classification; Angelin's posthumous 
work on the Swedish Crinoids, edited by Lindstrom (1878), 
likewise pays little attention to the results of zoological re- 
searches, although it displays a rich diversity of previously 
unknown forms in its beautiful illustrations. The works of 
Herbert Carpenter are therefore of very high value as investiga- 
tions based upon an equal familiarity with fossil and recent 
forms, and indicating the high-water mark of palaeontological 
and zoological researches at the time. Strictly scientific lines 
of research have also been adopted in all the more recent 
works. Two American scientists, Wachsmuth and Springer, 
have added very considerably to the knowledge of Echino- 
dermata, Wachsmuth's works extending through a period of 
twenty years, 1877-97; P. de Loriol has made a successful 
study of Mesozoic forms ; in England, F. A. Bather has con- 
tributed several memoirs on English and Swedish Crinoids 
(1890-93); in Germany, O. Jaekel has accomplished valuable 
new work on Palaeozoic Crinoids. 

The knowledge of the extinct order of the Cystoidea, erected 
by Buch, was advanced by the researches of Schmidt (1874) 
on representatives of the group from Russia, by those of 
Edward Forbes 1 (1848) on British forms, and by the works 
of Hall and Billings on North American Cystoids. In 1887 
Waagen edited a posthumous monograph on the Bohemian 
Cystoids by Barrande. The systematic arrangement and 
zoological position of the Cystoids have been discussed in 
recent years by Haeckel and Jaekel, but the results of their 
researches are much at variance. 

The small group of the Blastoids, discovered by Say in 1830, 
first underwent scientific examination at the hands of Ferdinand 
Roemer (1852). Subsequent work has extended our know- 

1 Edward Forbes, born 1815 in the Isle of Man, studied medicine and 
the natural sciences in London, Edinburgh, and Paris, travelled in Algeria, 
the Alps, and Asia Minor, and conducted in the yEgean Sea his famous 
investigations on the distribution of marine organisms at the different 
depths. In 1843 he accepted the Professorship of Botany at King's College 
in London, and when the Geological Survey was established he was selected 
as Palaeontologist and Professor of Natural History; shortly before his 
death, in 1854, he exchanged posts with the Professor of Natural History 
in Edinburgh. 


ledge of the specific forms, but could not add much to 
Roemer's fundamental observations and influences. The illus- 
trated catalogue of the British Museum contains an attractive 
account of the present knowledge about Blastoids, written by 
Robert Etheridg